code: def find_cells(self, column_family_id, column):
          
          try:
              column_family = self._cells[column_family_id]
          except KeyError:
              raise KeyError(_MISSING_COLUMN_FAMILY.format(column_family_id))
  
          try:
              cells = column_family[column]
          except KeyError:
              raise KeyError(_MISSING_COLUMN.format(column, column_family_id))
  
          return cells
docs: Get a time series of cells stored on this instance.
  
          For example:
  
          .. literalinclude:: snippets_table.py
              :start-after: [START bigtable_row_find_cells]
              :end-before: [END bigtable_row_find_cells]
  
          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 cells
                  are located.
  
          Returns:
              List[~google.cloud.bigtable.row_data.Cell]: The cells stored in the
              specified column.
  
          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``.