code: def transform(self, X, y=None):
      return self._transform(X)
  
imports: from array import array
  import numbers
  from operator import itemgetter
  import numpy
  import pandas
  import scipy.sparse
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.externals import six
  from auto_ml.utils import CustomLabelEncoder
label_desc: Use image node_id 6 for calling the DataFrameVectorizer obj's underlying member method code with example usage: obj.transform(X, y) and returns: self