code: function(command) {
  
  	// Backbone.model set() and Backbone.collection add() allow to pass an option parameter.
  	// That is also kept within the command. It skips validation if requested.
  	if (command.options && command.options.validation === false) return true;
  
  	var handoverErr;
  
  	_.each(this._map[command.action], function(route) {
  
  	    var i = 0;
  
  	    function callbacks(err) {
  
  		var fn = route[i++];
  
  		try {
  		    if (fn) {
  			fn(err, command, callbacks);
  		    } else {
  			handoverErr = err;
  			return;
  		    }
  		} catch (err) {
  		    callbacks(err);
  		}
  	    };
  
  	    callbacks(handoverErr);
  	});
  
  	if (handoverErr) {
  
  	    if (this.get('cancelInvalid')) this._commandManager.cancel();
  	    this.trigger('invalid', handoverErr);
  	    return false;
  	}
  
  	//command is valid
  	return true;
      }
docs: check whether the command is not against any rule