code: def gather_votes(self, candidates):
          
          votes = []
          for a in self.get_agents(addr=False):
              vote = a.vote(candidates)
              votes.append(vote)
          return votes
docs: Gather votes for the given candidates from the agents in the
          environment.
  
          Returned votes are anonymous, i.e. they cannot be tracked to any
          individual agent afterwards.
  
          :returns:
              A list of votes. Each vote is a list of ``(artifact, preference)``
              -tuples sorted in a preference order of a single agent.