check_limit( +{ one => 1, two => 2 });

##</code><code>##

sub check_limit {
   my %happyhash = @_;
   # It is now named %happyhash within the subroutine.
   my $num = keys %happyhash;
   print "Hash: happyhash has $num keys\n";
}

##</code><code>##

sub check_limit {
   my %happyhash = %{$_[0]};
   # It is now named %happyhash within the subroutine.
   my $num = keys %happyhash;
   print "Hash: happyhash has $num keys\n";
}