class_docstr: Base class for function transformers 
class_docstr_tok: ["Base","class","for","function","transformers"]
code: def fit(self, X, y=None):
      self.transformer_.fit(X, y=None)
      return self
  
imports: import warnings
  import pandas
  import numpy
  from scipy import sparse
  from sklearn.base import BaseEstimator, TransformerMixin
  from sklearn.preprocessing import MultiLabelBinarizer, FunctionTransformer, LabelEncoder, normalize
  from sklearn.feature_extraction.text import HashingVectorizer
  from sklearn import feature_selection
label_desc: Use image node_id 1 for calling the _CustomFunctionTransformer obj's underlying member method code with example usage: obj.fit(X, y) and returns: self