Count the total moves in a game range.

        Args:
          game_begin:  integer, starting game
          game_end:  integer, ending game

        Uses the `ct_` keyspace for rapid move summary.

def count_moves_in_game_range(self, game_begin, game_end):
        """Count the total moves in a game range.

        Args:
          game_begin:  integer, starting game
          game_end:  integer, ending game

        Uses the `ct_` keyspace for rapid move summary.
        """
        rows = self.bt_table.read_rows(
            ROWCOUNT_PREFIX.format(game_begin),
            ROWCOUNT_PREFIX.format(game_end),
            filter_=bigtable_row_filters.ColumnRangeFilter(
                METADATA, MOVE_COUNT, MOVE_COUNT))
        return sum([int(r.cell_value(METADATA, MOVE_COUNT)) for r in rows])