code: function _eventModifiers(e) {
          var modifiers = [];
  
          if (e.shiftKey) {
              modifiers.push('shift');
          }
  
          if (e.altKey) {
              modifiers.push('alt');
          }
  
          if (e.ctrlKey) {
              modifiers.push('ctrl');
          }
  
          if (e.metaKey) {
              modifiers.push('meta');
          }
  
          return modifiers;
      }
docs: takes a key event and figures out what the modifiers are
  
  @param {Event} e
  @returns {Array}