class_docstr: Helper class to allow construction of a list without
  having to reverse it in the end.
code: def append_plist(self, pl):
      return self._append(pl, lambda l: l)
  
imports: from collections.abc import Sequence, Hashable
  from numbers import Integral
  from functools import reduce
  from typing import Generic, TypeVar
label_desc: Use image node_id 4 for calling the _PListBuilder obj's underlying member method code with example usage: obj.append_plist(pl) and returns: self