using System;

static void FormatString(string stringToFormat)
{
    stringToFormat.Replace("World", "Mars");
}

static string FormatReturningString(string stringToFormat)
{
    return stringToFormat.Replace("Earth", "Mars");
}

var greetings = "Hello World!";

FormatString(greetings);
Console.WriteLine(greetings);

var anotherGreetings = "Good morning Earth!";
Console.WriteLine(FormatReturningString(anotherGreetings));



