NewCurriculum returns a collection of language tracks.

NewHomework decorates a problem set with some additional data based on the user's system.

HWAll represents all items in the collection.

HWNew represents problems that did not yet exist on the user's filesystem.

HWNotSubmitted represents problems that have not been submitted for review.

HWUpdated represents problems that were already on the user's filesystem, where one or more new files have been added.

TrackActive represents an active track.

TrackInactive represents an inactive track.

Curriculum is a collection of language tracks.

Homework is a collection of problems that were fetched from the APIs.

Item is a problem that has been fetched from the APIs.

HWFilter is used to categorize homework items.

Status is the status of a track (active/inactive).

SummaryOption is an alias of HWFilter that allows selective display of summary items.