docs: def raise_from(exc, cause):
      """
      Does the same as ``raise LALALA from BLABLABLA`` does in Python 3.
      But works in Python 2 also!
  
      Please checkout README on https://github.com/9seconds/pep3134
      to get an idea about possible pitfals. But short story is: please
      be pretty carefull with tracebacks. If it is possible, use sys.exc_info
      instead. But in most cases it will work as you expect.
      """
  
      context_tb = sys.exc_info()[2]
  
      incorrect_cause = not (
          (isinstance(cause, type) and issubclass(cause, Exception)) or
          isinstance(cause, BaseException) or
          cause is None
      )
      if incorrect_cause:
          raise TypeError("exception causes must derive from BaseException")
  
      if cause is not None:
          if not getattr(cause, "__pep3134__", False):
              # noinspection PyBroadException
              try:
                  raise_(cause)
              except:  # noqa pylint: disable=W0702
                  cause = sys.exc_info()[1]
          cause.__fixed_traceback__ = context_tb
  
      # noinspection PyBroadException
      try:
          raise_(exc)
      except:  # noqa pylint: disable=W0702
          exc = sys.exc_info()[1]
  
      exc.__original_exception__.__suppress_context__ = True
      exc.__original_exception__.__cause__ = cause
      exc.__original_exception__.__context__ = None
  
      raise exc