s = pybuiltin(:slice)
get(np.mgrid, (s(0,5), s(0,5))) works. (In general, foo[bar, baz] in Python needs to be get(foo, (bar,baz)) in PyCall at the moment, because foo[...] is used for attributes.) It would be nice if you could just use 0:5 here, but 0:5 is currently translated into an xrange object in Python, not a slice. I'm not sure if slice would be a better default translation? (I don't understand why Python has slice, xrange, and itertools.islice, all of which seem like they could be collapsed into a single type.)
