'Checks whether all dependencies in this ``DependencyTracker`` instance
are resolved.
>>> tracker = DependencyTracker()
>>> tracker.are_dependencies_resolved
True
>>> tracker.add(0, 1)
>>> tracker.are_dependencies_resolved
False
>>> tracker.resolve(0)
{1}
>>> tracker.are_dependencies_resolved
True
:return:
``True`` when all dependencies resolved, ``False`` if not.'

@property
def are_dependencies_resolved(self):

    return (not self._dependency_dict)
