sub match { 
  my $pattern=shift; 
  my $word=shift; 
   
  ## have to be exact 
  return unless length($pattern) == length($word); 
   
  my %seen; 
  my @pattern=split //,$pattern; 
  my @word=split //,$word; 
 
  for my $let (@word) { 
    my $pat=shift @pattern; 
    ## if this is a new pattern, make sure it doesn't 
    ## match a previous letter 
    if (!defined $seen{$pat}) { 
      ## bad if this letter exists 
      return if grep /$let/,join("",values %seen); 
      ## it's OK, 
      $seen{$pat}=$let; 
    } 
    else { 
      ## must be the same 
      return if $seen{$pat} ne $let; 
    } 
    ## tis good 
  } 
  1; 
}