input: Write a function to convert a given Python program to a C# program. 
  
  public int Power(int x, int y)
  {
      if (y == 0)
      {
          return 1;
      }
      else
      {
          return x * Power(x, y - 1);
      }
  }
  
  Assert Power(2, 3) == 8;
  Assert Power(3, 0) == 1;
  Assert Power(5, 2) == 25;
output: def Power(x, y):
      if y == 0:
          return 1
      else:
          return x * Power(x, y - 1)