text: /**
   * Safe and simple PHP isset() for JavaScript.
   *
   * Determine if a variable is considered set, this means if a variable is
   * declared and is different than null or undefined.
   *
   * If a variable has been unset with the delete keyword, it is no longer
   * considered to be set.
   *
   * isset() will return false when checking a variable that has been assigned to
   * null or undefined. Also note that a null character ("\0") is not equivalent
   * to the JavaScript null constant.
   *
   * If multiple parameters are supplied then isset() will return true only if
   * all of the parameters are considered set. Evaluation goes from left to right
   * and stops as soon as an unset variable is encountered.
   *
   * @param {Function} accessor Accessor functions returning the variable to be checked
   * @param {...Function} accessors Further accessors functions
   * @returns {Boolean} False if any accessor returns null or undefined
   */
  module.exports = function isset () {
    if (!arguments.length) throw new TypeError('isset requires at least one accessor function')
    return Array.prototype.slice.call(arguments).reduce((valid, accessor) => {
      if (typeof accessor !== 'function') throw new TypeError('isset requires accessors to be functions')
      try {
        return valid && accessor() !== undefined && accessor() !== null
      } catch (e) {
        return false
      }
    }, true)
  }
  