logs the agent details to logfile
        unique_name_file (list_agents.txtlist_agents_names.txt) = list of all instances of all agents

def _log_agent_name(self, unique_name_file):
        """
        logs the agent details to logfile
        unique_name_file (list_agents.txtlist_agents_names.txt) = list of all instances of all agents
        """
        agt_list = os.path.join(root_fldr, 'data', unique_name_file)
        if os.path.exists(agt_list):
            agents_logged = open(agt_list, 'r').read()
        else:
            agents_logged = ''
        print('agents_logged = ', agents_logged)
        if self._get_instance() not in agents_logged:
            with open(agt_list, 'a') as f:
                f.write(self._get_instance() + '\n')