my %h1 = %{ $_[0] }; #h2 similar

##</code><code>##

  my %h1 = (defined $_[0] and ref $_[0]) ? %{ $_[0] } : (); 

##</code><code>##



##</code><code>##

  scalar grep { 
    my ($a, $b) = ( $h1{$_}, $h2{$_} );
    ( not defined $a and defined $b )
      or
    ( not defined $b and defined $a )
      or
    $a ne $b 
  } @k1