sympy/sympy — pull request #7989 by skirpichev (2014-09-06 09:49:17+00:00)
Title: Implement a symbolic object for the relation "is an element of"

- [ ] naming (e.g. In, MemberOf, Element)
- [ ] move this class to the logic module?
- [ ] latex support and pretty-printing

(on top of the one commit from #7898)