code: function (val) {
    return (!behavior.enableUndefined || typeof val !== 'undefined')
      && (!behavior.enableNull || val !== null)
      && (!behavior.enableFalse || val !== false)
      && (!behavior.enableNaN || !Number.isNaN(val));
  }
docs: Checks if the provided value is defined.
  
  @method
  
  @param {*} val - The value on which to perform an existential check.
  
  @returns {boolean}