code: void check_command_exists(final String cmd_name) throws DevFailed {
  	final Vector cmd_list = device_class.get_command_list();
  	for (int i = 0; i < cmd_list.size(); i++) {
  	    final Command cmd = (Command) cmd_list.elementAt(i);
  	    if (cmd.get_name().toLowerCase().equals(cmd_name)) {
  		if (cmd.get_in_type() != Tango_DEV_VOID) {
  		    Except.throw_exception("API_IncompatibleCmdArgumentType", "Command " + cmd_name
  			    + " cannot be polled because it needs input value",
  			    "DeviceImpl.check_command_exists");
  		}
  		return;
  	    }
  	}
  
  	Except.throw_exception("API_CommandNotFound", "Command " + cmd_name + " not found",
  		"DeviceImpl.check_command_exists");
      }
docs: ==========================================================