def visit_Call(self, node):
    # If the function is wrapped by one of the marker decorators,
    # consider it graph ready.
    if anno.hasanno(node.func, 'live_val'):
      target_entity = anno.getanno(node.func, 'live_val')
      if target_entity in self.nocompile_decorators:
        if len(node.args) < 1:
          raise ValueError(
              'Found call to decorator function "%s", but it had no arguments. '
              'A decorator needs at least an argument.')
        anno.setanno(node.args[0], 'graph_ready', True)

    self.generic_visit(node)
    if anno.hasanno(node.func, 'live_val'):
      target_entity = anno.getanno(node.func, 'live_val')
      if anno.hasanno(node.func, 'fqn'):
        target_fqn = anno.getanno(node.func, 'fqn')
      if self._function_is_compilable(target_entity):
        node = self._rename_compilable_function(node)
      elif target_fqn in KNOWN_NUMPY_FUNCTIONS:
        # TODO(mdan): Should we replace these with equivalent TF ops instead?
        node = self._wrap_to_py_func_single_return(node, target_fqn)
      else:
        raise NotImplementedError(
            'py_func with return values (unknown function)')
    else:
      if self.context.recursive:
        node = self._insert_dynamic_conversion(node)
      else:
        # Unresolved functions are allowed in non-recursive mode.
        pass
    return node

  def visit_Call(self, node):
    # If the function is wrapped by one of the marker decorators,
    # consider it graph ready.
    if anno.hasanno(node.func, 'live_val'):
      target_entity = anno.getanno(node.func, 'live_val')
      if target_entity in self.nocompile_decorators:
        if len(node.args) < 1:
          raise ValueError(
              'Found call to decorator function "%s", but it had no arguments. '
              'A decorator needs at least an argument.')
        anno.setanno(node.args[0], 'graph_ready', True)

    self.generic_visit(node)
    if anno.hasanno(node.func, 'live_val'):
      target_entity = anno.getanno(node.func, 'live_val')
      if self._function_is_compilable(target_entity):
        node = self._rename_compilable_function(node)
      else:
        raise NotImplementedError('py_func with return values')
    else:
      if self.context.recursive:
        raise NotImplementedError('Could not resolve target function.')
      else:
        # TODO(mdan): Double check. Is this reachable code?
        pass
    return node

  def visit_Name(self, node):
    self.generic_visit(node)
    if isinstance(node.ctx, gast.Load):
      assert anno.hasanno(node, 'is_local'), node
      symbol_is_local = anno.getanno(node, 'is_local')
      assert anno.hasanno(node, 'is_modified_since_entry'), node
      symbol_is_modified = anno.getanno(node, 'is_modified_since_entry')
      assert anno.hasanno(node, 'is_param'), node
      symbol_is_param = anno.getanno(node, 'is_param')

      if not symbol_is_local and not symbol_is_param:
        if node.id in self.literals:
          anno.setanno(node, 'live_val', self.literals[node.id])
          # TODO(mdan): Could live values have FQNs? i.e. 'a'.join()
        elif node.id in self.context.namespace:
          obj = self.context.namespace[node.id]
          anno.setanno(node, 'live_val', obj)
          anno.setanno(node, 'fqn', (obj.__name__,))
        else:
          raise ValueError('Could not resolve symbol "%s".' % node.id)
      else:
        pass
        # TODO(mdan): Attempt to trace its value through the local chain.
        # TODO(mdan): Use type annotations as fallback.

      if not symbol_is_modified:
        if node.id in self.context.arg_values:
          obj = self.context.arg_values[node.id]
          anno.setanno(node, 'live_val', obj)
          anno.setanno(node, 'fqn', (obj.__class__.__name__,))
    return node

  def visit_Name(self, node):
    self.generic_visit(node)
    if isinstance(node.ctx, gast.Load):
      assert anno.hasanno(node, NodeAnno.IS_LOCAL), node
      symbol_is_local = anno.getanno(node, NodeAnno.IS_LOCAL)
      assert anno.hasanno(node, NodeAnno.IS_MODIFIED_SINCE_ENTRY), node
      symbol_is_modified = anno.getanno(node, NodeAnno.IS_MODIFIED_SINCE_ENTRY)
      assert anno.hasanno(node, NodeAnno.IS_PARAM), node
      symbol_is_param = anno.getanno(node, NodeAnno.IS_PARAM)

      if not symbol_is_local and not symbol_is_param:
        if node.id in self.literals:
          anno.setanno(node, 'live_val', self.literals[node.id])
          # TODO(mdan): Could live values have FQNs? i.e. 'a'.join()
        elif node.id in self.context.namespace:
          obj = self.context.namespace[node.id]
          anno.setanno(node, 'live_val', obj)
          anno.setanno(node, 'fqn', (obj.__name__,))
        else:
          pass
          # TODO(mdan): Should we raise an error here?
          # Can encounter this when:
          #  * a symbol truly lacks reference
          #  * a symbol is new, like the new name of a function we just renamed.
      else:
        pass
        # TODO(mdan): Attempt to trace its value through the local chain.
        # TODO(mdan): Use type annotations as fallback.

      if not symbol_is_modified:
        if node.id in self.context.arg_values:
          obj = self.context.arg_values[node.id]
          anno.setanno(node, 'live_val', obj)
          anno.setanno(node, 'fqn', (obj.__class__.__name__,))
    return node

 def visit_Call(self, node):
   if anno.hasanno(node.func, 'live_val'):
     # Symbols targeted by the "set_type" marker function are assigned the data
     # type that it specified.
     if (anno.getanno(node.func, 'live_val') is
         self.context.type_annotation_func):
       # Expecting the actual type to be the second argument.
       if len(node.args) != 2:
         raise ValueError('"%s" must have exactly two parameters'
                          % self.context.type_annotation_func)
       if not anno.hasanno(node.args[0], anno.Basic.QN):
         raise ValueError('the first argument of "%s" must by a symbol'
                          % self.context.type_annotation_func)
       if not anno.hasanno(node.args[1], 'live_val'):
         raise ValueError(
             'the second argument of "%s" must be statically resolvable' %
             self.context.type_annotation_func)
       target_symbol = anno.getanno(node.args[0], anno.Basic.QN)
       element_type = anno.getanno(node.args[1], 'live_val')
       # Find the definition of this symbol and annotate it with the given
       # data type. That in turn will cause future uses of the symbol
       # to receive the same type annotation.
       definition = self.scope.getval(target_symbol)
       anno.setanno(node, 'element_type', element_type)
       anno.setanno(definition, 'element_type', element_type)
       # TODO(mdan): Should we update references between definition and here?
   return self.generic_visit(node)

 def visit_Call(self, node):
   target = node.func
   if not anno.hasanno(target, 'live_val'):
     if not isinstance(target, gast.Attribute):
       # Suspecting this pattern would reach here:
       #   foo = bar
       #   foo()
       raise ValueError('Dont know how to handle dynamic functions.')
     if not isinstance(target.value, gast.Name):
       # Possible example of this kind:
       #   foo = module.Foo()
       #   foo.bar.baz()
       # TODO(mdan): This should be doable by using the FQN.
       raise ValueError('Dont know how to handle object properties yet.')
     # In the example below, object_source is 'tr.train.Optimizer()':
     #   opt = tf.train.Optimizer()
     #   opt.foo()
     if self.scope.hasval(target.value.id):
       object_source = self.scope.getval(target.value.id)
       if not anno.hasanno(object_source, 'type'):
         raise ValueError('Could not determine type of "%s". Is it dynamic?' %
                          (target.value.id))
       anno.setanno(target, 'type', anno.getanno(object_source, 'type'))
       anno.setanno(target, 'type_fqn', anno.getanno(object_source,
                                                     'type_fqn'))
     else:
       # TODO(mdan): Figure out what could the user do to get past this.
       raise ValueError('No info on "%s". Is it dynamically built?' %
                        (target.value.id))
   self.generic_visit(node)
   return node

  def _wrap_to_py_func_no_return(self, node):
    args_scope = anno.getanno(node, 'args_scope')
    # TODO(mdan): Properly handle varargs, kwargs, etc.
    args = tuple(gast.Name(n, gast.Load(), None) for n in args_scope.used)

    # pylint:disable=undefined-variable,unused-argument,function-redefined

    def template(call, wrapper, args):

      def wrapper(args):
        call(args)
        return 1

      tf.py_func(wrapper, [args], [tf.int64])

    # pylint:enable=undefined-variable,unused-argument,function-redefined

    wrapper_name = self.namer.compiled_function_name(node.func.id)
    wrapper_def, call_expr = templates.replace(
        template,
        call=node.func,
        wrapper=gast.Name(wrapper_name, gast.Load(), None),
        args=args)
    anno.setanno(call_expr.value, 'args_scope', args_scope)
    anno.setanno(wrapper_def, 'skip_processing', True)

    return (wrapper_def, call_expr)

  def visit_Call(self, node):
    # If the function is wrapped by one of the marker decorators,
    # consider it graph ready.
    if anno.hasanno(node.func, 'live_val'):
      target_obj = anno.getanno(node.func, 'live_val')
      if target_obj in self.nocompile_decorators:
        if len(node.args) < 1:
          raise ValueError(
              'Found call to decorator function "%s", but it had no arguments. '
              'A decorator needs at least an argument.')
        anno.setanno(node.args[0], 'graph_ready', True)

    self.generic_visit(node)
    if anno.hasanno(node.func, 'live_val'):
      target_obj = anno.getanno(node.func, 'live_val')
      if self._function_is_compilable(target_obj):
        node = self._rename_compilable_function(node)
      else:
        raise NotImplementedError('py_func with return values')
    elif anno.hasanno(node.func, 'type_fqn'):
      node = self._rename_member_function_of_known_type(node)
    else:
      raise NotImplementedError(
          'Member function call (of unknown type): %s.' % node.func.id)
    return node

  def _wrap_to_py_func_no_return(self, node):
    func_qn = anno.getanno(node.func, anno.Basic.QN)
    args_scope = anno.getanno(node, NodeAnno.ARGS_SCOPE)
    wrapper_name = self.context.namer.new_symbol(func_qn.ssf(),
                                                 args_scope.referenced)
    wrapper_args = []
    for arg in node.args:
      if anno.hasanno(arg, anno.Basic.QN):
        arg_qn = anno.getanno(arg, anno.Basic.QN)
      else:
        arg_qn = qual_names.QN('arg')
      wrapper_args.append(
          self.context.namer.new_symbol(arg_qn.ssf(), args_scope.referenced))
    # TODO(mdan): Properly handle varargs, kwargs, etc.
    # TODO(mdan): This is best handled as a dynamic dispatch.
    # That way we can separate tensors from non-tensor args.
    template = """
      def wrapper(wrapper_args):
        call(wrapper_args)
        return 1
      tf.py_func(wrapper, original_args, [tf.int64])
    """
    wrapper_def, call_expr = templates.replace(
        template,
        call=node.func,
        wrapper=wrapper_name,
        original_args=gast.List(elts=node.args, ctx=None),
        wrapper_args=wrapper_args)
    anno.setanno(wrapper_def, anno.Basic.SKIP_PROCESSING, True)

    return (wrapper_def, call_expr)

 def visit_With(self, node):
   current_scope = self.scope
   with_scope = Scope(current_scope, isolated=False)
   self.scope = with_scope
   self.generic_visit(node)
   anno.setanno(node, NodeAnno.BODY_SCOPE, with_scope)
   self.scope = current_scope
   return node

 def _as_function(self, func_name, args):
   template = """
     func_name(args)
   """
   replacement = templates.replace_as_expression(
       template, func_name=parser.parse_expression(func_name), args=args)
   anno.setanno(replacement, SAFE_BOOLEAN_OPERAND, True)
   return replacement

 def _inline_tf_op(self, op_name, args):
   template = """
     tf.op_name(args)
   """
   replacement = templates.replace(template, op_name=op_name, args=args)
   # It's a body with a single expression, we want its value.
   n = replacement[0].value
   anno.setanno(n, SAFE_BOOLEAN_OPERAND, True)
   return n

 def _process_block_node(self, node, block, scope_name):
   current_scope = self.scope
   block_scope = Scope(current_scope, isolated=False)
   self.scope = block_scope
   for n in block:
     self.visit(n)
   anno.setanno(node, '%s_scope' % scope_name, block_scope)
   self.scope = current_scope
   return node

 def visit_Print(self, node):
   current_scope = self.scope
   args_scope = Scope(current_scope)
   self.scope = args_scope
   for n in node.values:
     self.visit(n)
   anno.setanno(node, 'args_scope', args_scope)
   self.scope = current_scope
   return node

  def test_basic(self):
    node = ast.Name()

    self.assertFalse(anno.hasanno(node, 'foo'))
    with self.assertRaises(AttributeError):
      anno.getanno(node, 'foo')

    anno.setanno(node, 'foo', 3)
    self.assertTrue(anno.hasanno(node, 'foo'))
    self.assertEqual(3, anno.getanno(node, 'foo'))

 def _process_function_arg(self, arg_name):
   str_name = str(arg_name)
   if self.function_level == 1 and str_name in self.context.arg_types:
     # Forge a node to hold the type information, so that method calls on
     # it can resolve the type.
     type_holder = arg_name.ast()
     type_string, type_obj = self.context.arg_types[str_name]
     anno.setanno(type_holder, 'type', type_obj)
     anno.setanno(type_holder, 'type_fqn', tuple(type_string.split('.')))
     self.scope.setval(arg_name, type_holder)

  def test_copyanno(self):
    node_1 = ast.Name()
    anno.setanno(node_1, 'foo', 3)

    node_2 = ast.Name()
    anno.copyanno(node_1, node_2, 'foo')
    anno.copyanno(node_1, node_2, 'bar')

    self.assertTrue(anno.hasanno(node_2, 'foo'))
    self.assertFalse(anno.hasanno(node_2, 'bar'))

 def visit_FunctionDef(self, node):
   if self.scope:
     qn = QN(node.name)
     self.scope.mark_write(qn)
   current_scope = self.scope
   fndef_scope = Scope(current_scope, isolated=True)
   self.scope = fndef_scope
   self.generic_visit(node)
   anno.setanno(node, NodeAnno.BODY_SCOPE, fndef_scope)
   self.scope = current_scope
   return node

 def visit_Call(self, node):
   current_scope = self.scope
   args_scope = Scope(current_scope)
   self.scope = args_scope
   for n in node.args:
     self.visit(n)
   # TODO(mdan): Account starargs, kwargs
   for n in node.keywords:
     self.visit(n)
   anno.setanno(node, 'args_scope', args_scope)
   self.scope = current_scope
   self.visit(node.func)
   return node

 def visit_Call(self, node):
   current_scope = self.scope
   args_scope = Scope(current_scope, isolated=False)
   self.scope = args_scope
   for n in node.args:
     self.visit(n)
   # TODO(mdan): Account starargs, kwargs
   for n in node.keywords:
     self.visit(n)
   anno.setanno(node, NodeAnno.ARGS_SCOPE, args_scope)
   self.scope = current_scope
   self.visit(node.func)
   return node