code: def _invert_signs(signs):
      """Shall we invert signs?
      Invert if first (most probable) term is negative.
      """
      return signs[0] < 0
  
imports: from __future__ import absolute_import
  from collections import defaultdict, Counter
  from itertools import chain
  from typing import List, Iterable, Any, Dict, Tuple, Union
  import numpy
  import six
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.feature_extraction.text import HashingVectorizer, FeatureHasher
  from sklearn.pipeline import FeatureUnion
  from eli5._feature_names import FeatureNames
label_desc: Use image node_id 4 for calling a global function with example usage: _invert_signs(signs) and returns: unknown