$sub processarrays{
   my($a1, $a2) = @_;
   foreach(@$a1){ # dereferences $a1
      print $_;
   }
   for($i=0; $i<@$a2; $i++){
       print $a2->[$i];  #get at a particular index within array
   }
}
sub processhashes{
   my($h1,$h2)=@_;
   foreach my $key(keys %$h1){ #derefences $h1;
      print $h1->{$key};  #lookup based on $key
   }
}