code: function (shortcut, name, callback) {
  
                  if (this._collection[name] === undefined) {
                      this._collection[name] = {};
                  }
  
                  if (this._collection[name][shortcut] === undefined) {
                      this._collection[name][shortcut] = [];
                  }
  
                  this._collection[name][shortcut].push(callback);
  
                  return this;
  
              }
docs: Add a callback to a shortcut with given name.
  @param {(ch.onkeybackspace | ch.onkeytab | ch.onkeyenter | ch.onkeyesc | ch.onkeyleftarrow | ch.onkeyuparrow | ch.onkeyrightarrow | ch.onkeydownarrow)} shortcut Shortcut to subscribe.
  @param {String} name A name to add in the collection.
  @param {Function} callback A given function.
  @returns {Object} Retuns the ch.shortcuts.
  @example
  // Add a callback to ESC key with "component" name.
  ch.shortcuts.add(ch.onkeyesc, 'component', component.hide);