uirement? Those
  with few left should likely be worked on first, I guess?
* Are there any known conflicts for this requirement? We should
  probably work on those with the most known conflicts.

A sortable value should be returned (this will be used as the ``key``
parameter of the built-in sorting function). The smaller the value is,
the more preferred this requirement is (i.e. the sorting function
is called with ``reverse=False``).
r&