def pad(self, file, size=6):
        """Group together as many records as possible to fit in the specified size

        This SingleRecordStrategy will not group any record and will return them one by one as
        long as they are within the maximum size.

        Args:
            file (str): file path to read the records from.
            size (int): maximum size in MB that each group of records will be fitted to.
                passing 0 means unlimited size.

        Returns:
             generator of records
        """
        for element in self.splitter.split(file):
            if _validate_payload_size(element, size):
                yield element