class_docstr: Applies `impute_null` as a FunctionTransformer
  
  Args:
      impute_val (object): value to impute with
class_docstr_tok: ["Applies","`","impute_null","`","as","a","FunctionTransformer","Args",":","impute_val","(","object",")",":","value","to","impute","with"]
code: def __init__(self, impute_val=None):
      self.transformer_ = FunctionTransformer(
          impute_null,
          kw_args={"impute_val": impute_val},
          validate=False,
      )
  
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 to create a new ImputeNull object from inherited base classes: _CustomFunctionTransformer with example: obj = ImputeNull(impute_val)