class_docstr: Layer to generate mask.
code: def size_feature_name(self):
      return self._size_feature_name
  
imports: import six
  import tensorflow.compat.v2
  from tensorflow.python.feature_column import feature_column_lib
  from tensorflow_ranking.python import utils
label_desc: Use image node_id 3 for calling the GenerateMask obj's underlying member method code with example usage: obj.size_feature_name() and returns: self