code: def installedRequirements(self, target):
      
      myDepends = dependentsOf(self.__class__)
      for dc in self.store.query(_DependencyConnector,
                                 _DependencyConnector.target == target):
          if dc.installee.__class__ in myDepends:
              yield dc.installee
docs: Return an iterable of things installed on the target that this
      item requires.