pylint: generate stubs for more methods

__getitem__ was missing causing unsubscriptable-object on BTrees
4 jobs for zope4py3 in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Zope4Py3

01:39:21

failed ERP5.CodingStyleTest-Zope4Py3-py2

01:00:27

failed ERP5.UnitTest-Zope4Py3

03:56:21

failed ERP5.UnitTest-Zope4Py3-Py2

03:35:36