using System;
// etc.
Console.WriteLine("Hello,World!");

using static System.Console;
// etc.
WriteLine("Hello,World");

public boolIsSquare(Rectangle rect)
{
  return rect.Height == rect.Width;
}

public boolIsSquare(Rectangle rect) => rect.Height == rect.Width;

public string FullName
{
  get
  {
    return FirstName +"" + LastName;
  }
}

public string FullName=> FirstName +"" + LastName;

public class Person
{
  public Person()
  {
    Age = 24;
  }
  public int Age {get; set;}
}

public class Person
{
  public int Age {get; set;} = 42;
}

private readonly int_bookId;
public BookId
{
  get
  {
    return _bookId;
  }
}

public BookId {get;}

public void Method(objecto)
{
  if (o == null) throw newArgumentNullException("o"); 

public void Method(objecto)
{
  if (o == null) throw newArgumentNullException(nameof(o)); 

int? age = p == null ?null : p.Age;

int? age = p?.Age;

var handler = Event;
if (handler != null)
{
  handler(source, e);
}

handler?.Invoke(source,e);

public override ToString()
{
  return string.Format("{0}, {1}",Title, Publisher);
} 

public override ToString()=> $"{Title} {Publisher}";

var dict = newDictionary<int, string>();
dict.Add(3,"three");
dict.Add(7,"seven");

var dict = newDictionary<int, string>()
{
  [3] ="three",
  [7] ="seven"
};

try
{
  //etc.
}
catch (MyException ex)
{
  if (ex.ErrorCode != 405) throw;
  // etc.
}

try
{
  //etc.
}
catch (MyException ex)when (ex.ErrorCode == 405)
{
  // etc.
}

bool hasError = false;
string errorMessage =null;
try
{
//etc.
}
catch (MyException ex)
{
  hasError = true;
  errorMessage = ex.Message;
}
if (hasError)
{
  await newMessageDialog().ShowAsync(errorMessage);
}

try
{
  //etc.
}
catch (MyException ex)
{
  await newMessageDialog().ShowAsync(ex.Message);
}