def add_getter(cls, attr, func_name):
    ''' "Monkey-patch" in a getter method to access a mangled attribute;

        add_getter(cls, '__attr', 'fn') is equivalent to "cls.fn = lambda self: self.__attr"'''
    from compiler.misc import mangle
    assert attr.startswith("__")
    def _getter(self): return getattr(self, mangle(attr, cls.__name__))
    setattr(cls, func_name, _getter)

def add_setter(cls, attr, func_name):
    ''' "Monkey-patch" in a setter method to set a mangled attribute;

        add_setter(cls, '__attr', 'fn') is equivalent to "cls.fn = lambda self: self.__attr"'''
    from compiler.misc import mangle
    assert attr.startswith("__")
    def _setter(self, val): setattr(self, mangle(attr, cls.__name__), val)
    setattr(cls, func_name, _setter)

# Usage examples
import pyparsing as pyp

add_getter(pyp.ParseResults, '__tokdict', 'get_tokdict')
add_setter(pyp.ParseResults, '__tokdict', 'set_tokdict')

element = <some pyparsing Element>
results = element.parseString(some_string)

print(results.__tokdict)      # Fails, obviously
print(results.get_tokdict())  # Succeeds