code: def _set_cell(self, column_family_id, column, value, timestamp=None, state=None):
          
          column = _to_bytes(column)
          if isinstance(value, six.integer_types):
              value = _PACK_I64(value)
          value = _to_bytes(value)
          if timestamp is None:
              # Use -1 for current Bigtable server time.
              timestamp_micros = -1
          else:
              timestamp_micros = _microseconds_from_datetime(timestamp)
              # Truncate to millisecond granularity.
              timestamp_micros -= timestamp_micros % 1000
  
          mutation_val = data_v2_pb2.Mutation.SetCell(
              family_name=column_family_id,
              column_qualifier=column,
              timestamp_micros=timestamp_micros,
              value=value,
          )
          mutation_pb = data_v2_pb2.Mutation(set_cell=mutation_val)
          self._get_mutations(state).append(mutation_pb)
docs: Helper for :meth:`set_cell`
  
          Adds a mutation to set the value in a specific cell.
  
          ``state`` is unused by :class:`DirectRow` but is used by
          subclasses.
  
          :type column_family_id: str
          :param column_family_id: The column family that contains the column.
                                   Must be of the form
                                   ``[_a-zA-Z0-9][-_.a-zA-Z0-9]*``.
  
          :type column: bytes
          :param column: The column within the column family where the cell
                         is located.
  
          :type value: bytes or :class:`int`
          :param value: The value to set in the cell. If an integer is used,
                        will be interpreted as a 64-bit big-endian signed
                        integer (8 bytes).
  
          :type timestamp: :class:`datetime.datetime`
          :param timestamp: (Optional) The timestamp of the operation.
  
          :type state: bool
          :param state: (Optional) The state that is passed along to
                        :meth:`_get_mutations`.