code: function isEmpty (val) {
    if (null == val) return true;
    if ('number' == typeof val) return 0 === val;
    if (undefined !== val.length) return 0 === val.length;
    for (var key in val) if (has.call(val, key)) return false;
    return true;
  }
docs: Test whether a value is "empty".
  
  @param {Mixed} val
  @return {Boolean}