reverse LIST
            In list context, returns a list value consisting of the elements
            of LIST in the opposite order. In scalar context, concatenates the
            elements of LIST and returns a string value with all characters in
            the opposite order.

                print join(", ", reverse "world", "Hello"); # Hello, world

                print scalar reverse "dlrow ,", "olleH";    # Hello, world

            Used without arguments in scalar context, "reverse" reverses $_.

                $_ = "dlrow ,olleH";
                print reverse;                         # No output, list context
                print scalar reverse;                  # Hello, world