code: def __len__(self):
      return len(self._dict)
  
imports: import itertools
  import numpy
  from ._matrix import spmatrix
  from ._base import _spbase, sparray, issparse
  from ._index import IndexMixin
  from ._sputils import isdense, getdtype, isshape, isintlike, isscalarlike, upcast, upcast_scalar, check_shape
label_desc: Use image node_id 6 for calling the _dok_base obj's underlying member method code with example usage: obj.__len__() and returns: len