code: func (a *API) executeRobotDeviceCommand(res http.ResponseWriter, req *http.Request) {
  	if _, err := a.jsonDeviceFor(req.URL.Query().Get(":robot"),
  		req.URL.Query().Get(":device")); err != nil {
  		a.writeJSON(map[string]interface{}{"error": err.Error()}, res)
  	} else {
  		a.executeCommand(
  			a.master.Robot(req.URL.Query().Get(":robot")).
  				Device(req.URL.Query().Get(":device")).(gobot.Commander).
  				Command(req.URL.Query().Get(":command")),
  			res,
  			req,
  		)
  	}
  }
docs: // executeRobotDeviceCommand calls a device command associated to requested route