sub is_empty_list
{
	return @{$_[0]} == 0;
}


# remove ($what, $list, $howmany)
#
# Removes $what from the list $list up to $howmany times.
# If $howmany is not provided, removes all occurrences of $what.
#
sub remove
{
	my $what = $_[0];
	my $list = $_[1];
	my $howmany = defined $_[2] ? $_[2] : -1;
	my @ret = ();
	
	foreach my $elem (@{$list})
	{
		push @ret, $elem unless ($elem == $what and $howmany-- > 0);
	}

	return \@ret;
}