class_docstr: Suggests an architecture based on the Harmonica algorithm.
docstr: Expand to polynomial features.
docstr_tok: ["Expand","to","polynomial","features","."]
code: def _get_polynomial_expansion(self, feature_extender, x):
      """Expand to polynomial features."""
      return feature_extender.fit_transform(np.array(x))
  
imports: import cmath
  import os
  from absl import logging
  from model_search import block_builder
  from model_search.architecture import architecture_utils
  from model_search.search import search_algorithm
  import numpy
  from sklearn import linear_model
  from sklearn import preprocessing
  import tensorflow.compat.v2
label_desc: Use image node_id 2 for calling the Harmonica obj's underlying member method code with example usage: obj._get_polynomial_expansion(feature_extender, x) and returns: feature_extender