reverse_string(STRING): return a reversed copy of the input string

reverse.pl

# Normally, you'd just say
#   reverse STRING
# since Perl provides a builtin for this functionality, but that would be
# cheating based on the rules of the assignment.

#    my $desrever = reverse_string(STRING);
#
#  Return a reversed copy of the input string.
sub reverse_string {
  return join '', reverse split //, $_[0];
}