astropy/astropy — pull request #1521 by astrofrog (2013-10-05 13:27:23+00:00)
Title: Feature request: have Unit.is_equivalent take tuples

I found myself wanting to do:

```
value.unit.is_equivalent((u.erg/u.s, u.erg/u.cm**2, u.Jy))
```

but had to split it up into multiple checks. It might be worth supporting this (in the same way that ``isinstance`` does)