Say I have a list: 

`l1 = [[1, 3], [3, 2], [2, 1]]`

I want to push each item in `l1` to a binary heap, 'memory' but sorted in the binary heap by `each_item[-1]`.

I've tried: `heapq.heappush(_heap, item=itemgetter(-1))` and the equivilent using an anonymous function but I get:

`TypeError: heappush() takes no keyword arguments`