code: def get_missing_dependencies(self, broker):
          
          missing_required = [r for r in self.requires if r not in broker]
          missing_at_least_one = [d for d in self.at_least_one if not set(d).intersection(broker)]
          if missing_required or missing_at_least_one:
              return (missing_required, missing_at_least_one)
docs: Gets required and at-least-one dependencies not provided by the broker.