Current returns the current user.

Lookup looks up a user by username.

LookupGroup looks up a group by name.

LookupGroupId looks up a group by groupid.

LookupId looks up a user by userid.

Group represents a grouping of users.

User represents a user account.

UnknownGroupError is returned by LookupGroup when a group cannot be found.

UnknownGroupIdError is returned by LookupGroupId when a group cannot be found.

UnknownUserError is returned by Lookup when a user cannot be found.

UnknownUserIdError is returned by LookupId when a user cannot be found.