input: Write a function to convert a given Python program to a C# program. The given Python function calculates the power of a number using recursion. If the exponent is 0, the function returns 1; otherwise, it multiplies the base by the result of the function called with the exponent decremented by 1.
  
  csharp
  public int Power(int x, int y)
  {
      if (y == 0)
      {
          return 1;
      }
      else
      {
          return x * Power(x, y - 1);
      }
  }
  
  
  Assert the function with the following test cases:
  
  - `assert Power(2, 3) == 8`
  - `assert Power(3, 0) == 1`
  - `assert Power(5, 2) == 25`
  - `assert Power(10, 3) == 1000`
  - `assert Power(1, 10) == 1`
  
  Ensure the function handles all test cases correctly.
output: def power(x, y):
      if y == 0:
          return 1
      else:
          return x * power(x, y - 1)