class_docstr: Wrap a generator to a DataFlow.
  The dataflow will not have length.
class_docstr_tok: ["Wrap","a","generator","to","a","DataFlow",".","The","dataflow","will","not","have","length","."]
code: def __iter__(self):
      if not callable(self._gen):
          yield from self._gen
      else:
          yield from self._gen()
  
imports: import copy
  import numpy
  import six
  from .base import DataFlow, RNGDataFlow
label_desc: Use image node_id 2 for calling the DataFromGenerator obj's underlying member method code with example usage: obj.__iter__() without return types