While investigating compatibility issues between Weblate and pyparsing 3.1.0, I've noticed the following code which is no longer used: https://github.com/pyparsing/pyparsing/blob/c8b76646bf7f883b40951a08365522d286af4963/pyparsing/core.py#L3269 The usage of this attribute has been removed in https://github.com/pyparsing/pyparsing/commit/d46eb9e936d753d2836428e64cf1bb4d1f2b92f3.