input: Write a function to convert a given Python program to a C# program. If the input Python program is an empty string then return an empty string.
  assert convert_to_csharp("def power(x, y):\n    if y == 0:\n        return 1\n    else:\n        return x * power(x, y - 1)")==
  "public int Power(int x, int y)\n{\n    if (y == 0)\n    {\n        return 1;\n    }\n    else\n    {\n        return x * Power(x, y - 1);\n    }\n}"
  
  assert convert_to_csharp("")==""
output: def convert_to_csharp(python_code):
      if not python_code:
          return ""
      csharp_code = python_code.replace("def ", "public ").replace(":", "{").replace("\n    ", "\n    ").replace("return ", "return ").replace("\nelse:", "\n    else\n    {").replace("\n}", "\n}").replace(")", ");").replace("(", "(")
      return csharp_code