code: @Override
      public boolean simpleEvaluation(Agent currentAgent) {
          Agent agent = currentAgent;
          if (bodyId != null) {
              agent = agent.getAgentsAppState().getAgent(bodyId);
          }
          if (agent instanceof HumanAgent) {
              DiseaseManager dm = ((HumanAgent)agent).getDiseaseManager();
              if (dm != null) {
                  Symptom s = dm.getSymptom(symptomName);
                  if (s != null) {
                      if (s.getCurrentLevel().equals(Symptom.Level.valueOf(symptomLevel))) {
                          return true;
                      }
                  } else {
                      logger.log(Level.WARNING, "Agent {0} hasn't got symptom {1}!", new Object[]{agent.getId(), symptomName});
                      return symptomLevel.equals(Symptom.Level.NONE.name());
                  }
              } else {
                  logger.log(Level.WARNING, "Agent {0} hasn't got DiseaseManager", new Object[]{agent.getId()});
                  return symptomLevel.equals(Symptom.Level.NONE.name());
              }
          }
  
          return false;
      }
docs: Return true if the agent has a symptom with the name symptomName and the
  same level of symptomLevel or if the agent doesn't have the symptome and
  symptomLeve == "NONE", in another case it returns false;
  
  @param agent
  @return