code: def __len__(self) -> int:
      return self._len
  
imports: from __future__ import annotations
  import copyreg
  import pkgutil
  import types
  from typing import TYPE_CHECKING, cast
  import numpy
  import dedupe.variables
  from dedupe.variables.base import FieldType
  from dedupe.variables.base import MissingDataType, Variable
  from dedupe.variables.interaction import InteractionType
label_desc: Use image node_id 2 for calling the DataModel obj's underlying member method code with example usage: obj.__len__() and returns: self