code: function _del (hotkey) {
          var combo = (hotkey instanceof Hotkey) ? hotkey.combo : hotkey;
  
          Mousetrap.unbind(combo);
  
          if (angular.isArray(combo)) {
            var retStatus = true;
            var i = combo.length;
            while (i--) {
              retStatus = _del(combo[i]) && retStatus;
            }
            return retStatus;
          } else {
            var index = scope.hotkeys.indexOf(_get(combo));
  
            if (index > -1) {
              // if the combo has other combos bound, don't unbind the whole thing, just the one combo:
              if (scope.hotkeys[index].combo.length > 1) {
                scope.hotkeys[index].combo.splice(scope.hotkeys[index].combo.indexOf(combo), 1);
              } else {
  
                // remove hotkey from bound scopes
                angular.forEach(boundScopes, function (boundScope) {
                  var scopeIndex = boundScope.indexOf(scope.hotkeys[index]);
                  if (scopeIndex !== -1) {
                      boundScope.splice(scopeIndex, 1);
                  }
                });
  
                scope.hotkeys.splice(index, 1);
              }
              return true;
            }
          }
  
          return false;
  
        }
docs: delete and unbind a Hotkey
  
  @param  {mixed} hotkey   Either the bound key or an instance of Hotkey
  @return {boolean}        true if successful