sub is_contained ($$$) {
    my ( $some_legal_range, $gene_legal_range, $legal_length ) = @_;

    ### save result for later use:
    my $range_length = legal_range_length($some_legal_range)
        or return 0;

#    if ( legal_range_length($some_legal_range) == 0 ) {
#        return 0;
#    }

    my $intersection_legal_range =
      intersect_legal_ranges( $some_legal_range, $gene_legal_range,
        $legal_length );

    return ( legal_range_length($intersection_legal_range) == $range_length );

#    if ( legal_range_length($intersection_legal_range) ==
#        legal_range_length($some_legal_range) )  ### <- already did this call
#    {
#        return 1;
#    }
#    return 0;
}

# ...

sub intersect_legal_ranges($$$) {
    my ( $legal_range_1, $legal_range_2, $legal_length ) = @_;

    my $intersections_a = [];

    my $intersect_h;  ### let's declare this in advance

    for ( my $i = 0 ; $i < scalar( @{$legal_range_1} ) ; $i++ ) {
        for ( my $j = 0 ; $j < scalar( @{$legal_range_2} ) ; $j++ ) {
            $intersect_h = intersect_simple_ranges( ${$legal_range_1}[$i],
                ${$legal_range_2}[$j] ) and     ### only push what you'll use
                push @{$intersections_a}, $intersect_h;
        }
    }
    $intersections_a = flatten_simple_ranges( $intersections_a, $legal_length );
}

sub flatten_simple_ranges($$) {
    my ( $simple_range_a, $legal_length ) = @_;

    my $legal_range = [];
    my $last_to     = undef;

#    # filter out undef
#    $simple_range_a = [ grep { $_ } @{$simple_range_a} ];  ### <- not needed
    ...