class_docstr: Wrap an iterable of datapoints to a DataFlow
class_docstr_tok: ["Wrap","an","iterable","of","datapoints","to","a","DataFlow"]
code: def __len__(self):
      if self._len is None:
          raise NotImplementedError
      return self._len
  
imports: import copy
  import numpy
  import six
  from .base import DataFlow, RNGDataFlow
label_desc: Use image node_id 2 for calling the DataFromIterable obj's underlying member method code with example usage: obj.__len__() and returns: self