Constructs a new object implementing the WorkUnitQuery interface.

function O.work.query(workType)

Create a work unit query object.

If the optional workType is specified, the query will find the given type of work unit. If the workType does not contain a : character, an exception will be thrown.

If workType is not specified, then you must either call ref() or tag() so that your query returns an acceptable number of work units.