docstr: Returns label columns of transformed DataFrame
code: def get_label_columns(self, squeeze=True):
      """
      Returns label columns of transformed DataFrame
      """
      if not self.train_called:
          raise Exception("apply_train should be called first")
      if not self.is_regression:
          new_lab_cols = self.c
      else:
          new_lab_cols = self.label_columns
      return (
          new_lab_cols[0]
          if len(new_lab_cols) == 1 and squeeze
          else new_lab_cols
      )
  
imports: from .imports import *
  from subprocess import Popen
label_desc: Use image node_id 2 for calling the YTransformDataFrame obj's underlying member method code with example usage: obj.get_label_columns(squeeze) and returns: unknown