def add_magic_hook(ctx) -> None:
    info = ctx.cls.info
    str_type = ctx.api.named_type_or_none('builtins.str', [])
    assert str_type is not None
    var = Var('__magic__', str_type)
    var.info = info
    info.names['__magic__'] = SymbolTableNode(MDEF, var)

        def add_method(funcname: str,
                       ret: Type,
                       args: List[Argument],
                       name: Optional[str] = None,
                       is_classmethod: bool = False,
                       is_new: bool = False,
                       ) -> None:
            if is_classmethod or is_new:
                first = [Argument(Var('cls'), TypeType.make_normalized(selftype), None, ARG_POS)]
            else:
                first = [Argument(Var('self'), selftype, None, ARG_POS)]
            args = first + args

            types = [arg.type_annotation for arg in args]
            items = [arg.variable.name() for arg in args]
            arg_kinds = [arg.kind for arg in args]
            assert None not in types
            signature = CallableType(cast(List[Type], types), arg_kinds, items, ret,
                                     function_type)
            signature.variables = [tvd]
            func = FuncDef(funcname, args, Block([]))
            func.info = info
            func.is_class = is_classmethod
            func.type = set_callable_name(signature, func)
            func._fullname = info.fullname() + '.' + funcname
            if is_classmethod:
                v = Var(funcname, func.type)
                v.is_classmethod = True
                v.info = info
                v._fullname = func._fullname
                dec = Decorator(func, [NameExpr('classmethod')], v)
                info.names[funcname] = SymbolTableNode(MDEF, dec)
            else:
                info.names[funcname] = SymbolTableNode(MDEF, func)

    def visit_FunctionDef(self, n: ast35.FunctionDef) -> Node:
        args = self.transform_args(n.args, n.lineno)

        arg_kinds = [arg.kind for arg in args]
        arg_names = [arg.variable.name() for arg in args]
        arg_types = None  # type: List[Type]
        if n.type_comment is not None:
            try:
                func_type_ast = ast35.parse(n.type_comment, '<func_type>', 'func_type')
            except SyntaxError:
                raise TypeCommentParseError(TYPE_COMMENT_SYNTAX_ERROR, n.lineno)
            assert isinstance(func_type_ast, ast35.FunctionType)
            # for ellipsis arg
            if (len(func_type_ast.argtypes) == 1 and
                    isinstance(func_type_ast.argtypes[0], ast35.Ellipsis)):
                arg_types = [a.type_annotation if a.type_annotation is not None else AnyType()
                             for a in args]
            else:
                arg_types = [a if a is not None else AnyType() for
                            a in TypeConverter(line=n.lineno).visit_list(func_type_ast.argtypes)]
            return_type = TypeConverter(line=n.lineno).visit(func_type_ast.returns)

            # add implicit self type
            if self.in_class() and len(arg_types) < len(args):
                arg_types.insert(0, AnyType())
        else:
            arg_types = [a.type_annotation for a in args]
            return_type = TypeConverter(line=n.lineno).visit(n.returns)

        if isinstance(return_type, UnboundType):
            return_type.is_ret_type = True

        func_type = None
        if any(arg_types) or return_type:
            func_type = CallableType([a if a is not None else AnyType() for a in arg_types],
                                     arg_kinds,
                                     arg_names,
                                     return_type if return_type is not None else AnyType(),
                                     None)

        func_def = FuncDef(n.name,
                       args,
                       self.as_block(n.body, n.lineno),
                       func_type)
        if func_type is not None:
            func_type.definition = func_def
            func_type.line = n.lineno

        if n.decorator_list:
            var = Var(func_def.name())
            var.is_ready = False
            var.set_line(n.decorator_list[0].lineno)

            func_def.is_decorated = True
            func_def.set_line(n.lineno + len(n.decorator_list))
            func_def.body.set_line(func_def.get_line())
            return Decorator(func_def, self.visit_list(n.decorator_list), var)
        else:
            return func_def

 def make_accessors(self, n: Var) -> List[Node]:
     if n.type:
         t = n.type
     else:
         t = AnyType()
     return [self.make_getter_wrapper(n.name(), t),
             self.make_setter_wrapper(n.name(), t),
             self.make_dynamic_getter_wrapper(n.name(), t),
             self.make_dynamic_setter_wrapper(n.name(), t)]

 def analyse_member_lvalue(self, lval):
     lval.accept(self)
     if self.is_init_method and isinstance(lval.expr, NameExpr):
         node = (lval.expr).node
         if isinstance(node, Var) and (node).is_self and lval.name not in self.type.vars:
             lval.is_def = True
             v = Var(lval.name)
             v.info = self.type
             v.is_ready = False
             lval.def_var = v
             self.type.vars[lval.name] = v

 def build_enum_call_typeinfo(self, name: str, items: List[str], fullname: str) -> TypeInfo:
     base = self.api.named_type_or_none(fullname)
     assert base is not None
     info = self.api.basic_new_typeinfo(name, base)
     info.metaclass_type = info.calculate_metaclass_type()
     info.is_enum = True
     for item in items:
         var = Var(item)
         var.info = info
         var.is_property = True
         var._fullname = '{}.{}'.format(self.api.qualified_name(name), item)
         info.names[item] = SymbolTableNode(MDEF, var)
     return info

    def visit_FunctionDef(self, n):
        args = self.transform_args(n.args, n.lineno)

        arg_kinds = [arg.kind for arg in args]
        arg_names = [arg.variable.name() for arg in args]
        if n.type_comment is not None:
            func_type_ast = typed_ast.parse(n.type_comment, '<func_type>', 'func_type')
            arg_types = [a if a is not None else AnyType() for
                         a in TypeConverter(line=n.lineno).visit(func_type_ast.argtypes)]
            return_type = TypeConverter(line=n.lineno).visit(func_type_ast.returns)

            # add implicit self type
            if self.in_class and len(arg_types) < len(args):
                arg_types.insert(0, AnyType())
        else:
            arg_types = [a.type_annotation for a in args]
            return_type = TypeConverter(line=n.lineno).visit(n.returns)

        func_type = None
        if any(arg_types) or return_type:
            func_type = CallableType([a if a is not None else AnyType() for a in arg_types],
                                     arg_kinds,
                                     arg_names,
                                     return_type if return_type is not None else AnyType(),
                                     None)

        func_def = FuncDef(n.name,
                       args,
                       self.as_block(n.body, n.lineno),
                       func_type)
        if func_type is not None:
            func_type.definition = func_def

        if n.decorator_list:
            var = Var(func_def.name())
            var.is_ready = False
            var.set_line(n.decorator_list[0].lineno)

            func_def.is_decorated = True
            func_def.set_line(n.lineno + len(n.decorator_list))
            func_def.body.set_line(func_def.get_line())
            return Decorator(func_def, self.visit(n.decorator_list), var)
        else:
            return func_def

 def add_field(var: Var, is_initialized_in_class: bool = False,
               is_property: bool = False) -> None:
     var.info = info
     var.is_initialized_in_class = is_initialized_in_class
     var.is_property = is_property
     var._fullname = '%s.%s' % (info.fullname(), var.name())
     info.names[var.name()] = SymbolTableNode(MDEF, var)

 def analyse_lvalue(self, lval, nested=False, add_defs=False):
     if isinstance(lval, NameExpr):
         n = lval
         nested_global = not self.locals and self.block_depth > 0 and not self.type
         if (add_defs or nested_global) and n.name not in self.globals:
             # Define new global name.
             v = Var(n.name)
             v._full_name = self.qualified_name(n.name)
             v.is_ready = False  # Type not inferred yet
             n.node = v
             n.is_def = True
             n.kind = GDEF
             n.full_name = v._full_name
             self.globals[n.name] = SymbolTableNode(GDEF, v, self.cur_mod_id)
         elif isinstance(n.node, Var) and n.is_def:
             v = n.node
             self.module_names[v.name()] = SymbolTableNode(GDEF, v, self.cur_mod_id)
         elif self.locals and n.name not in self.locals[-1] and n.name not in self.global_decls[-1]:
             # Define new local name.
             v = Var(n.name)
             n.node = v
             n.is_def = True
             n.kind = LDEF
             self.add_local(v, n)
         elif not self.locals and (self.type and n.name not in self.type.vars):
             # Define a new attribute.
             v = Var(n.name)
             v.info = self.type
             v.is_initialized_in_class = True
             n.node = v
             n.is_def = True
             self.type.vars[n.name] = v
         else:
             # Bind to an existing name.
             lval.accept(self)
     elif isinstance(lval, MemberExpr):
         if not add_defs:
             self.analyse_member_lvalue(lval)
     elif isinstance(lval, IndexExpr):
         if not add_defs:
             lval.accept(self)
     elif isinstance(lval, ParenExpr):
         self.analyse_lvalue((lval).expr, nested, add_defs)
     elif (isinstance(lval, TupleExpr) or isinstance(lval, ListExpr)) and not nested:
         items = (lval).items
         for i in items:
             self.analyse_lvalue(i, True, add_defs)
     else:
         self.fail("Invalid assignment target", lval)

def analyze_var(
    name: str,
    var: Var,
    itype: Instance,
    info: TypeInfo,
    node: Context,
    is_lvalue: bool,
    msg: MessageBuilder,
    not_ready_callback: Callable[[str, Context], None],
) -> Type:
    """Analyze access to an attribute via a Var node.

    This is conceptually part of analyze_member_access and the arguments are similar.
    """
    # Found a member variable.
    itype = map_instance_to_supertype(itype, var.info)
    typ = var.type
    if typ:
        if isinstance(typ, PartialType):
            return handle_partial_attribute_type(typ, is_lvalue, msg, var)
        t = expand_type_by_instance(typ, itype)
        if is_lvalue and var.is_property and not var.is_settable_property:
            # TODO allow setting attributes in subclass (although it is probably an error)
            msg.read_only_property(name, info, node)
        if var.is_initialized_in_class and isinstance(t, FunctionLike):
            if is_lvalue:
                if var.is_property:
                    if not var.is_settable_property:
                        msg.read_only_property(name, info, node)
                else:
                    msg.cant_assign_to_method(node)

            if not var.is_staticmethod:
                # Class-level function objects and classmethods become bound
                # methods: the former to the instance, the latter to the
                # class.
                functype = t
                check_method_type(functype, itype, var.is_classmethod, node, msg)
                signature = method_type(functype)
                if var.is_property:
                    # A property cannot have an overloaded type => the cast
                    # is fine.
                    return cast(CallableType, signature).ret_type
                else:
                    return signature
        return t
    else:
        if not var.is_ready:
            not_ready_callback(var.name(), node)
        # Implicit 'Any' type.
        return AnyType()

def _make_frozen(ctx: 'mypy.plugin.ClassDefContext', attributes: List[Attribute]) -> None:
    """Turn all the attributes into properties to simulate frozen classes."""
    for attribute in attributes:
        if attribute.name in ctx.cls.info.names:
            # This variable belongs to this class so we can modify it.
            node = ctx.cls.info.names[attribute.name].node
            assert isinstance(node, Var)
            node.is_property = True
        else:
            # This variable belongs to a super class so create new Var so we
            # can modify it.
            var = Var(attribute.name, ctx.cls.info[attribute.name].type)
            var.info = ctx.cls.info
            var._fullname = '%s.%s' % (ctx.cls.info.fullname(), var.name())
            ctx.cls.info.names[var.name()] = SymbolTableNode(MDEF, var)
            var.is_property = True

def analyze_var(
    name: str, var: Var, itype: Instance, info: TypeInfo, node: Context, is_lvalue: bool, msg: MessageBuilder
) -> Type:
    """Analyze access to an attribute via a Var node.

    This is conceptually part of analyze_member_access and the arguments are similar.
    """
    # Found a member variable.
    itype = map_instance_to_supertype(itype, var.info)
    if var.type:
        t = expand_type_by_instance(var.type, itype)
        if var.is_initialized_in_class and isinstance(t, FunctionLike):
            if is_lvalue:
                if var.is_property:
                    if not var.is_settable_property:
                        msg.read_only_property(name, info, node)
                else:
                    msg.cant_assign_to_method(node)

            if not var.is_staticmethod:
                # Class-level function objects and classmethods become bound
                # methods: the former to the instance, the latter to the
                # class.
                functype = cast(FunctionLike, t)
                check_method_type(functype, itype, node, msg)
                signature = method_type(functype)
                if var.is_property:
                    # A property cannot have an overloaded type => the cast
                    # is fine.
                    return cast(CallableType, signature).ret_type
                else:
                    return signature
        return t
    else:
        if not var.is_ready:
            msg.cannot_determine_type(var.name(), node)
        # Implicit 'Any' type.
        return AnyType()

 def visit_var(self, node: Var) -> None:
     node.info = self.fixup(node.info)
     self.fixup_type(node.type)
     super().visit_var(node)

 def make_init_arg(var: Var) -> Argument:
     default = default_items.get(var.name(), None)
     kind = ARG_POS if default is None else ARG_OPT
     return Argument(var, var.type, default, kind)

    def visit_FunctionDef(self, n: ast27.FunctionDef) -> Statement:
        converter = TypeConverter(self.errors, line=n.lineno)
        args, decompose_stmts = self.transform_args(n.args, n.lineno)

        arg_kinds = [arg.kind for arg in args]
        arg_names = [arg.variable.name() for arg in args]  # type: List[Optional[str]]
        arg_names = [None if argument_elide_name(name) else name for name in arg_names]
        if special_function_elide_names(n.name):
            arg_names = [None] * len(arg_names)

        arg_types = None  # type: List[Type]
        if (n.decorator_list and any(is_no_type_check_decorator(d) for d in n.decorator_list)):
            arg_types = [None] * len(args)
            return_type = None
        elif n.type_comment is not None and len(n.type_comment) > 0:
            try:
                func_type_ast = ast35.parse(n.type_comment, '<func_type>', 'func_type')
                assert isinstance(func_type_ast, ast35.FunctionType)
                # for ellipsis arg
                if (len(func_type_ast.argtypes) == 1 and
                        isinstance(func_type_ast.argtypes[0], ast35.Ellipsis)):
                    arg_types = [a.type_annotation if a.type_annotation is not None else AnyType()
                                for a in args]
                else:
                    # PEP 484 disallows both type annotations and type comments
                    if any(a.type_annotation is not None for a in args):
                        self.fail(messages.DUPLICATE_TYPE_SIGNATURES, n.lineno, n.col_offset)
                    arg_types = [a if a is not None else AnyType() for
                                a in converter.translate_expr_list(func_type_ast.argtypes)]
                return_type = converter.visit(func_type_ast.returns)

                # add implicit self type
                if self.in_class() and len(arg_types) < len(args):
                    arg_types.insert(0, AnyType())
            except SyntaxError:
                self.fail(TYPE_COMMENT_SYNTAX_ERROR, n.lineno, n.col_offset)
                arg_types = [AnyType()] * len(args)
                return_type = AnyType()
        else:
            arg_types = [a.type_annotation for a in args]
            return_type = converter.visit(None)

        for arg, arg_type in zip(args, arg_types):
            self.set_type_optional(arg_type, arg.initializer)

        if isinstance(return_type, UnboundType):
            return_type.is_ret_type = True

        func_type = None
        if any(arg_types) or return_type:
            if len(arg_types) != 1 and any(isinstance(t, EllipsisType) for t in arg_types):
                self.fail("Ellipses cannot accompany other argument types "
                          "in function type signature.", n.lineno, 0)
            elif len(arg_types) > len(arg_kinds):
                self.fail('Type signature has too many arguments', n.lineno, 0)
            elif len(arg_types) < len(arg_kinds):
                self.fail('Type signature has too few arguments', n.lineno, 0)
            else:
                func_type = CallableType([a if a is not None else AnyType() for a in arg_types],
                                        arg_kinds,
                                        arg_names,
                                        return_type if return_type is not None else AnyType(),
                                        None)

        body = self.as_block(n.body, n.lineno)
        if decompose_stmts:
            body.body = decompose_stmts + body.body
        func_def = FuncDef(n.name,
                       args,
                       body,
                       func_type)
        if func_type is not None:
            func_type.definition = func_def
            func_type.line = n.lineno

        if n.decorator_list:
            var = Var(func_def.name())
            var.is_ready = False
            var.set_line(n.decorator_list[0].lineno)

            func_def.is_decorated = True
            func_def.set_line(n.lineno + len(n.decorator_list))
            func_def.body.set_line(func_def.get_line())
            return Decorator(func_def, self.translate_expr_list(n.decorator_list), var)
        else:
            return func_def

 def visit_var(self, node: Var) -> Var:
     # Note that a Var must be transformed to a Var.
     if node in self.var_map:
         return self.var_map[node]
     new = Var(node.name(), self.optional_type(node.type))
     new.line = node.line
     new._fullname = node._fullname
     new.info = node.info
     new.is_self = node.is_self
     new.is_ready = node.is_ready
     new.is_initialized_in_class = node.is_initialized_in_class
     new.is_staticmethod = node.is_staticmethod
     new.is_classmethod = node.is_classmethod
     new.is_property = node.is_property
     new.set_line(node.line)
     self.var_map[node] = new
     return new

def analyze_var(name: str,
                var: Var,
                itype: Instance,
                info: TypeInfo,
                mx: MemberContext, *,
                implicit: bool = False) -> Type:
    """Analyze access to an attribute via a Var node.

    This is conceptually part of analyze_member_access and the arguments are similar.

    itype is the class object in which var is defined
    original_type is the type of E in the expression E.var
    if implicit is True, the original Var was created as an assignment to self
    """
    # Found a member variable.
    itype = map_instance_to_supertype(itype, var.info)
    typ = var.type
    if typ:
        if isinstance(typ, PartialType):
            return mx.chk.handle_partial_var_type(typ, mx.is_lvalue, var, mx.context)
        t = expand_type_by_instance(typ, itype)
        if mx.is_lvalue and var.is_property and not var.is_settable_property:
            # TODO allow setting attributes in subclass (although it is probably an error)
            mx.msg.read_only_property(name, itype.type, mx.context)
        if mx.is_lvalue and var.is_classvar:
            mx.msg.cant_assign_to_classvar(name, mx.context)
        result = t
        if var.is_initialized_in_class and isinstance(t, FunctionLike) and not t.is_type_obj():
            if mx.is_lvalue:
                if var.is_property:
                    if not var.is_settable_property:
                        mx.msg.read_only_property(name, itype.type, mx.context)
                else:
                    mx.msg.cant_assign_to_method(mx.context)

            if not var.is_staticmethod:
                # Class-level function objects and classmethods become bound methods:
                # the former to the instance, the latter to the class.
                functype = t
                # Use meet to narrow original_type to the dispatched type.
                # For example, assume
                # * A.f: Callable[[A1], None] where A1 <: A (maybe A1 == A)
                # * B.f: Callable[[B1], None] where B1 <: B (maybe B1 == B)
                # * x: Union[A1, B1]
                # In `x.f`, when checking `x` against A1 we assume x is compatible with A
                # and similarly for B1 when checking agains B
                dispatched_type = meet.meet_types(mx.original_type, itype)
                check_self_arg(functype, dispatched_type, var.is_classmethod, mx.context, name,
                               mx.msg)
                signature = bind_self(functype, mx.original_type, var.is_classmethod)
                if var.is_property:
                    # A property cannot have an overloaded type => the cast is fine.
                    assert isinstance(signature, CallableType)
                    result = signature.ret_type
                else:
                    result = signature
    else:
        if not var.is_ready:
            mx.not_ready_callback(var.name(), mx.context)
        # Implicit 'Any' type.
        result = AnyType(TypeOfAny.special_form)
    fullname = '{}.{}'.format(var.info.fullname(), name)
    hook = mx.chk.plugin.get_attribute_hook(fullname)
    if result and not mx.is_lvalue and not implicit:
        result = analyze_descriptor_access(mx.original_type, result, mx.builtin_type,
                                           mx.msg, mx.context, chk=mx.chk)
    if hook:
        result = hook(AttributeContext(mx.original_type, result, mx.context, mx.chk))
    return result

    def visit_FunctionDef(self, n: ast27.FunctionDef) -> Statement:
        lineno = n.lineno
        converter = TypeConverter(self.errors, line=lineno,
                                  assume_str_is_unicode=self.unicode_literals)
        args, decompose_stmts = self.transform_args(n.args, lineno)

        arg_kinds = [arg.kind for arg in args]
        arg_names = [arg.variable.name() for arg in args]  # type: List[Optional[str]]
        arg_names = [None if argument_elide_name(name) else name for name in arg_names]
        if special_function_elide_names(n.name):
            arg_names = [None] * len(arg_names)

        arg_types = []  # type: List[Optional[Type]]
        type_comment = n.type_comment
        if (n.decorator_list and any(is_no_type_check_decorator(d) for d in n.decorator_list)):
            arg_types = [None] * len(args)
            return_type = None
        elif type_comment is not None and len(type_comment) > 0:
            try:
                func_type_ast = ast3_parse(type_comment, '<func_type>', 'func_type')
                assert isinstance(func_type_ast, ast3.FunctionType)
                # for ellipsis arg
                if (len(func_type_ast.argtypes) == 1 and
                        isinstance(func_type_ast.argtypes[0], ast3.Ellipsis)):
                    arg_types = [a.type_annotation
                                 if a.type_annotation is not None
                                 else AnyType(TypeOfAny.unannotated)
                                 for a in args]
                else:
                    # PEP 484 disallows both type annotations and type comments
                    if any(a.type_annotation is not None for a in args):
                        self.fail(message_registry.DUPLICATE_TYPE_SIGNATURES, lineno, n.col_offset)
                    arg_types = [a if a is not None else AnyType(TypeOfAny.unannotated) for
                                 a in converter.translate_expr_list(func_type_ast.argtypes)]
                return_type = converter.visit(func_type_ast.returns)

                # add implicit self type
                if self.in_class() and len(arg_types) < len(args):
                    arg_types.insert(0, AnyType(TypeOfAny.special_form))
            except SyntaxError:
                self.fail(TYPE_COMMENT_SYNTAX_ERROR, lineno, n.col_offset)
                arg_types = [AnyType(TypeOfAny.from_error)] * len(args)
                return_type = AnyType(TypeOfAny.from_error)
        else:
            arg_types = [a.type_annotation for a in args]
            return_type = converter.visit(None)

        for arg, arg_type in zip(args, arg_types):
            self.set_type_optional(arg_type, arg.initializer)

        func_type = None
        if any(arg_types) or return_type:
            if len(arg_types) != 1 and any(isinstance(t, EllipsisType) for t in arg_types):
                self.fail("Ellipses cannot accompany other argument types "
                          "in function type signature.", lineno, 0)
            elif len(arg_types) > len(arg_kinds):
                self.fail('Type signature has too many arguments', lineno, 0)
            elif len(arg_types) < len(arg_kinds):
                self.fail('Type signature has too few arguments', lineno, 0)
            else:
                any_type = AnyType(TypeOfAny.unannotated)
                func_type = CallableType([a if a is not None else any_type for a in arg_types],
                                        arg_kinds,
                                        arg_names,
                                        return_type if return_type is not None else any_type,
                                        _dummy_fallback)

        body = self.as_required_block(n.body, lineno)
        if decompose_stmts:
            body.body = decompose_stmts + body.body
        func_def = FuncDef(n.name,
                       args,
                       body,
                       func_type)
        if isinstance(func_def.type, CallableType):
            # semanal.py does some in-place modifications we want to avoid
            func_def.unanalyzed_type = func_def.type.copy_modified()
        if func_type is not None:
            func_type.definition = func_def
            func_type.line = lineno

        if n.decorator_list:
            var = Var(func_def.name())
            var.is_ready = False
            var.set_line(n.decorator_list[0].lineno)

            func_def.is_decorated = True
            func_def.set_line(lineno + len(n.decorator_list))
            func_def.body.set_line(func_def.get_line())
            dec = Decorator(func_def, self.translate_expr_list(n.decorator_list), var)
            dec.set_line(lineno, n.col_offset)
            return dec
        else:
            # Overrides set_line -- can't use self.set_line
            func_def.set_line(lineno, n.col_offset)
            return func_def

 def _reset_var_final_flags(self, v: Var) -> None:
     v.is_final = False
     v.final_unset_in_class = False
     v.final_set_in_init = False
     v.final_value = None

 def add(self, name: str, type: Type) -> Var:
     v = Var(name)
     v.type = type
     self.names[name] = v
     return v