text: /**
   * @param {unknown} thing
   * @returns {boolean}
   */
  export function whitespace(thing) {
    /** @type {string} */
    var value =
      // @ts-ignore looks like a node.
      thing && typeof thing === 'object' && thing.type === 'text'
        ? // @ts-ignore looks like a text.
          thing.value || ''
        : thing
  
    // HTML whitespace expression.
    // See <https://html.spec.whatwg.org/#space-character>.
    return typeof value === 'string' && value.replace(/[ \t\n\f\r]/g, '') === ''
  }
  