sub expand
{
	local $_ = shift;
	if ( /^(.*?)\{([^}]+)\}(.*)$/ )
	{
		my( $pre, $spec, $post ) = ( $1, $2, $3 );
		return map expand($pre.$_.$post), split /,/, $spec
	}
	if ( /^(.*?)\[(\d+):(\d+)\](.*)$/ )
	{
		my( $pre, $lo, $hi, $post ) = ( $1, $2, $3, $4 );
		return map expand($pre.$_.$post), $lo .. $hi
	}
	$_
}