code: function isChecked(token) {
      var checked = false;
  
      if (token.content.indexOf('[x]') === 0 || token.content.indexOf('[X]') === 0) {
          checked = true;
      }
  
      return checked;
  }
docs: Return boolean value whether task checked or not
  @param {object} token Token object
  @returns {boolean}
  @ignore