class_docstr: Test statistic holder for Wald-type tests
  
  Parameters
  ----------
  stat : float
      The test statistic
  df : int
      Degree of freedom.
  null : str
      A statement of the test's null hypothesis
  alternative : str
      A statement of the test's alternative hypothesis
  name : str, default "" (empty)
      Name of test
code: def alternative(self) -> str:
      return self._alternative
  
file_path: arch/arch/utility/testing.py
imports: from __future__ import annotations
  from functools import cached_property
  from scipy.stats import chi2
label_desc: Use image node_id 6 for calling the WaldTestStatistic obj's underlying member method code with example usage: obj.alternative() and returns: self