using System;
public static class stringExtension
{
    public static string Reverse(base string s)
    {
        char[] msv = s.ToCharArray();
        Array.Reverse(msv);
        return new string(msv);
    }
}

using System;
public static class stringExtension
{
    public static string Reverse(this string s)
    {
        char[] msv = s.ToCharArray();
        Array.Reverse(msv);
        return new string(msv);
    }
}

using System;
public static class stringExtension
{
    public static string Reverse(super string s)
    {
        char[] msv = s.ToCharArray();
        Array.Reverse(msv);
        return new string(msv);
    }
}