Interesting, converting the string return value of .ToUpper() to a MyString type instead of converting the MyString s to a built-in string type. I'm curious if there's any particular advantage there, or if it just keeps things a little simpler on one side of the equation?

I should have refactored based on what I learned when researching how to get the length of an int (without stringifying it) in golang, but I am satisfied that I managed to avoid strconv, and definitely learned better ways to get this one done from the other solutions!