feature: exit early on 'empty'

[roycewilliams]

A 'nice' to have, and only if it's easy to detect:

if there are no elements left in the target, quit early - stop removing, and skip reading additional files.

A naive way to do this might be accumulate the number of removed elements, and if it exceeds the target element count, quit. But I'm not sure if this is a robust method.