isUndefined (value) {
    return value === undefined
  }
Return whether the provided value is a `undefined`.

@example
import { utils } from 'js-data';
const a = undefined;
const b = { foo: "bar"};
console.log(utils.isUndefined(a)); // true
console.log(utils.isUndefined(b.baz)); // true
console.log(utils.isUndefined(b)); // false
console.log(utils.isUndefined(b.foo)); // false

@method utils.isUndefined
@param {*} value The value to test.
@returns {boolean} Whether the provided value is a `undefined`.
@since 3.0.0