[Datetime-SIG] hashability of tzinfo objects

This is tied in with the equality semantics of these objects, has come up here, in the dateutil tracker, and in pandas: https://mail.python.org/archives/list/datetime-sig@python.org/thread/45P3EXY... / <https://mail.python.org/archives/list/datetime-sig@python.org/thread/45P3EXY3OJM56MJJH57VJ7NZEBXG7HG4/> https://github.com/dateutil/dateutil/issues/835 https://github.com/dateutil/dateutil/issues/792 https://github.com/pandas-dev/pandas/pull/24006#discussion_r238483612 My understanding is that hashing cannot be implemented until/unless equality is changed. Is that accurate? Is there a compelling reason for these _not_ to be hashable?