code: def cell_value(self, column_family_id, column, index=0):
          
          cells = self.find_cells(column_family_id, column)
  
          try:
              cell = cells[index]
          except (TypeError, IndexError):
              num_cells = len(cells)
              msg = _MISSING_INDEX.format(index, column, column_family_id, num_cells)
              raise IndexError(msg)
  
          return cell.value
docs: Get a single cell value stored on this instance.
  
          For example:
  
          .. literalinclude:: snippets_table.py
              :start-after: [START bigtable_row_cell_value]
              :end-before: [END bigtable_row_cell_value]
  
          Args:
              column_family_id (str): The ID of the column family. Must be of the
                  form ``[_a-zA-Z0-9][-_.a-zA-Z0-9]*``.
              column (bytes): The column within the column family where the cell
                  is located.
              index (Optional[int]): The offset within the series of values. If
                  not specified, will return the first cell.
  
          Returns:
              ~google.cloud.bigtable.row_data.Cell value: The cell value stored
              in the specified column and specified index.
  
          Raises:
              KeyError: If ``column_family_id`` is not among the cells stored
                  in this row.
              KeyError: If ``column`` is not among the cells stored in this row
                  for the given ``column_family_id``.
              IndexError: If ``index`` cannot be found within the cells stored
                  in this row for the given ``column_family_id``, ``column``
                  pair.