private static function hours_helper($piece) { $out = new self(); if(strpos($piece, '-') !== False) { $limits = explode('-', $piece); $lower = $limits[0]; $upper = $limits[1]; foreach(range($lower, $upper) as $hour) { $out->add_single(new Hour($hour)); } } elseif(strpos($piece, ':') !== False) { $nums = explode(':', $piece); $out->add_single(new Hour($nums[0], $nums[1])); } else { $out->add_single(new Hour($piece)); } return $out; }