foreach $motiffile(@motiffile){
        if($motiffile =~ /(^[A|S]\d+\s+|^[A|S]\d+b\s+)([A-Z]+)(\s+.*)$
+/){
        my $name = $1;
        my $site = $2;
        $regexp = IUB_to_regexp($site);
        $motif_hash{$name} = "$site $regexp\n";
        print "motif : $site\n";
        print "The regexp : $regexp\n";
        }     
           }    
           return $regexp;
         ...

##</code><code>##

push @regexp, $regexp

##</code><code>##

return join '|', @regexp;