PO::read_line( resource $f, string $action = 'read' ): bool

467		public function read_line( $f, $action = 'read' ) {468			static $last_line     = '';469			static $use_last_line = false;470			if ( 'clear' === $action ) {471				$last_line = '';472				return true;473			}474			if ( 'put-back' === $action ) {475				$use_last_line = true;476				return true;477			}478			$line          = $use_last_line ? $last_line : fgets( $f );479			$line          = ( "\r\n" === substr( $line, -2 ) ) ? rtrim( $line, "\r\n" ) . "\n" : $line;480			$last_line     = $line;481			$use_last_line = false;482			return $line;483		}