  */
      disabled: {
        type: Boolean,
        value: false
      },

      /**
       * Returns true if the value is invalid. Bind this to both the `<paper-input-container>`'s
       * and the input's `invalid` property.
       */
      invalid: {
        type: Boolean,
        value: false,
        notify: true
      },

      /**
       * Set to true to prevent the user from entering invalid input. Bind this to the
       * `<input is="iron-input">`'s `preventInvalidInput` property.
       */
    