def _move_agent(self, agent, direction, wrap_allowed=True):
        """
        moves agent 'agent' in 'direction'
        """
        x,y = agent.coords['x'], agent.coords['y']
        print('moving agent ', agent.name, 'to x,y=', direction, 'wrap_allowed = ', wrap_allowed)
        agent.coords['x'] = x + direction[0]
        agent.coords['y'] = y + direction[1]