my $DEBUG = 0;   # set to > 0 for debugging, the bigger the value the more verbose

# in the code wherever you think it useful
$DEBUG && DEBUG( 2, "some message" );


sub DEBUG {
    my ( $debug_level, $message ) = @_;
    # see if we want this message a current debug level
  return if $debug_level > $DEBUG;
    # we can get info on where this info comes from from caller()
    my ( $package, $file, $line ) = caller();
    # print a standard format message, say line num and message
    warn "$line\t\$message\n";
}