def read_row(self, row_key, filter_=None):
        """Read a single row from this table.

        For example:

        .. literalinclude:: snippets_table.py
            :start-after: [START bigtable_read_row]
            :end-before: [END bigtable_read_row]

        :type row_key: bytes
        :param row_key: The key of the row to read from.

        :type filter_: :class:`.RowFilter`
        :param filter_: (Optional) The filter to apply to the contents of the
                        row. If unset, returns the entire row.

        :rtype: :class:`.PartialRowData`, :data:`NoneType <types.NoneType>`
        :returns: The contents of the row if any chunks were returned in
                  the response, otherwise :data:`None`.
        :raises: :class:`ValueError <exceptions.ValueError>` if a commit row
                 chunk is never encountered.
        """
        row_set = RowSet()
        row_set.add_row_key(row_key)
        result_iter = iter(self.read_rows(filter_=filter_, row_set=row_set))
        row = next(result_iter, None)
        if next(result_iter, None) is not None:
            raise ValueError("More than one row was returned.")
        return row