docstr: Feature engineering step callable that requests, modifies, and returns datasets
code: def f(self) -> Callable:
      """Feature engineering step callable that requests, modifies, and returns datasets"""
      return self._f
  
imports: from hyperparameter_hunter.keys.hashing import make_hash_sha256
  from hyperparameter_hunter.space.dimensions import Categorical, RejectedOptional
  from hyperparameter_hunter.utils.boltons_utils import remap, default_visit, default_enter
  from hyperparameter_hunter.utils.general_utils import subdict
  import ast
  from contextlib import suppress
  from inspect import getsource
  import numpy
  import pandas
  from typing import List, Callable, Dict, Union, Tuple
label_desc: Use image node_id 6 for calling the EngineerStep obj's underlying member method code with example usage: obj.f() and returns: self