sub foo {
    my ($hash1,$hash2) = @_;

    # cleaner dereference
    foreach (keys %$hash1) {
        print "$_ $hash1->{$_}\n";
    }

    # preferred, if you need to access both
    while ( my ($key, $value) = each %$hash2 ) {
       print "$key $value\n";
    }
}