class_docstr:     A function decorator that will append an addendum to the docstring
      of the target function.
  
      This decorator should be robust even if func.__doc__ is None
      (for example, if -OO was passed to the interpreter).
  
      Usage: construct a docstring.Appender with a string to be joined to
      the original docstring. An optional 'join' parameter may be supplied
      which will be used to join the docstring and addendum. e.g.
  
      add_copyright = Appender("Copyright (c) 2009", join='
  ')
  
      @add_copyright
      def my_dog(has='fleas'):
          "This docstring will have a copyright below"
          pass
      
code: def __call__(self, func: T) -> T:
      func.__doc__ = func.__doc__ if func.__doc__ else ""
      self.addendum = self.addendum if self.addendum else ""
      docitems = [func.__doc__, self.addendum]
      func.__doc__ = dedent(self.join.join(docitems))
      return func
  
imports: from __future__ import annotations
  from functools import wraps
  import inspect
  from textwrap import dedent
  from typing import Any, Callable, Mapping, cast
  import warnings
  from pandas._libs.properties import cache_readonly
  from pandas._typing import F, T
  from pandas.util._exceptions import find_stack_level
label_desc: Use image node_id 2 for calling the Appender obj's underlying member method code with example usage: obj.__call__(func) and returns: func