Comparer interface; compares a value to another value of the same type.
CompareTo
Compare a value to another value of the same type; should return 0 if equal, 1 if more, -1 if less.
method CompareTo(a: T): Int32
Int32 CompareTo(T a)
func CompareTo(_ a: T) -> Int32
Function CompareTo(a As T) As Int32
Parameters: