class_docstr: Test-focused class to simplify accessing values by attribute
code: def __str__(self):
      ss = "\n".join(
          str(k) + " = " + str(v).replace("\n", "\n    ")
          for k, v in vars(self).items()
      )
      return ss
  
file_path: statsmodels/statsmodels/tools/testing.py
imports: from statsmodels.compat.pandas import testing
  import numpy.testing
  import pandas
  from statsmodels.tools.tools import Bunch
label_desc: Use image node_id 2 for calling the Holder obj's underlying member method code with example usage: obj.__str__() and returns: ss