code: def set_job(estimators, preprocessing):
      """Set job to run"""
      if estimators is None:
          if preprocessing is None:
              raise ValueError(
                  "Need to specify at least one of"
                  "[estimators, preprocessing]"
              )
          else:
              job = "preprocess"
      elif preprocessing is None:
          job = "evaluate"
      else:
          job = "preprocess-evaluate"
      return job
  
file_path: mlens/mlens/model_selection/_base_functions.py
imports: from __future__ import division
  from collections import Counter
  from ..parallel import EvalLearner, EvalTransformer, Pipeline
  from ..utils.formatting import _assert_format
  from ..utils.checks import assert_valid_estimator
  from ..externals.sklearn.base import clone
label_desc: Use image node_id 4 for calling a global function with example usage: set_job(estimators, preprocessing) and returns: job