class_docstr: Base class for Transformations that returns exactly one result per input in
  the stream.
class_docstr_tok: ["Base","class","for","Transformations","that","returns","exactly","one","result","per","input","in","the","stream","."]
code: def __call__(
      self, data_it: Iterable[DataEntry], is_train: bool
  ) -> Iterator:
      for data_entry in data_it:
          try:
              yield self.map_transform(data_entry.copy(), is_train)
          except Exception as e:
              raise e
  
imports: import abc
  from dataclasses import dataclass
  from typing import Callable, Iterable, Iterator, List
  from gluonts.core.component import equals, validated
  from gluonts.dataset.common import DataEntry, Dataset
  from gluonts.env import env
label_desc: Use image node_id 1 for calling the MapTransformation obj's underlying member method code with example usage: obj.__call__(data_it, is_train) without return types