`o.or (some a) = o.getD a`. As discussed on [Zulip](https://leanprover.zulipchat.com/#narrow/channel/217875-Is-there-code-for-X.3F/topic/a.2Eor.20.28some.20b.29.20.3D.20a.2EgetD.20b/near/472785093). |
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| Attach.lean | ||
| Basic.lean | ||
| BasicAux.lean | ||
| Instances.lean | ||
| Lemmas.lean | ||
| List.lean | ||