code: def _return_generators(generators):
      """Sets the number of towers to zero when generator isn't used."""
      for generator_name in base_tower_generator.ALL_GENERATORS:
          if generator_name not in generators.keys():
              architecture_utils.set_number_of_towers(generator_name, 0)
  
      return generators
  
imports: import abc
  import collections
  from absl import logging
  from model_search.architecture import architecture_utils
  from model_search.generators import base_tower_generator
  from model_search.generators import trial_utils
  from model_search.generators.prior_generator import PriorGenerator
  from model_search.generators.replay_generator import ReplayGenerator
  from model_search.generators.search_candidate_generator import SearchCandidateGenerator
label_desc: Use image node_id 1 for calling a global function with example usage: _return_generators(generators) and returns: generators