def one(self, filter_by=None):
        """
        Parameters
        ----------
        filter_by: callable, default None
            Callable must take one argument (a record of table), and return True to keep record, or False to skip it.
            Example : .one(lambda x: x.name == "my_name").
            If None, records are not filtered.

        Returns
        -------
        Record instance if one and only one record is found. Else raises.

        Raises
        ------
        RecordDoesNotExistError if no record is found
        MultipleRecordsReturnedError if multiple records are found
        """
        return Queryset(self, records=self._records.values()).one(filter_by=filter_by)
Parameters
        ----------
        filter_by: callable, default None
            Callable must take one argument (a record of table), and return True to keep record, or False to skip it.
            Example : .one(lambda x: x.name == "my_name").
            If None, records are not filtered.

        Returns
        -------
        Record instance if one and only one record is found. Else raises.

        Raises
        ------
        RecordDoesNotExistError if no record is found
        MultipleRecordsReturnedError if multiple records are found