[Soc2014] Official meta API

+1 to what @timgraham said. filter + lambda strikes me as a notation you only use if you really like functional programming, or you're stuck on Python 2.2 :-)

As for adding hidden_related_objects - while that does simplify the logic in that one line, it means adding a public API for something that is used in exactly one place. I'd rather see this single implementation be a little more complex than try and modify the public API to be more complex to accommodate a single use case.