#!/usr/bin/perl
use warnings;
use strict;

print grep{!/intron/ unless /splice_region&intron/}<DATA>;

#Update: the English explanation:
# exclude lines with "intron" except if that line
# contains "splice_region&intron". 

=Prints:
whehehe shshshs hshshsh #should pass thru
som splice_region&intron intron 98797 #should pass
wqer splice_region&intron poiy #should pass

=cut


__DATA__
something intron asdfasdf #should be deleted
whehehe shshshs hshshsh #should pass thru
som splice_region&intron intron 98797 #should pass
wqer splice_region&intron poiy #should pass