using System;
using System.Collections.Generic;
using System.Linq;
public static class MyExtensions1feăfew
{
public static string ToUpperCase(this string str)
return str.ToLower();
}
static class Program
static void Main()
string myString = "heAllo";
string upperString = myString.ToUpperCase(); // Using the extension method
Console.WriteLine(upperString); // Output: HELLO