(2) As used in this section:
(a) "Disposable earnings" means that part of the earnings of an individual remaining after the deduction from those earnings of amounts required by law to be withheld; and
(b) "Assignment of earnings" includes all forms of assignments, deductions, transfers, or sales of earnings to another, either as payment or as security, and whether stated to be revocable or nonrevocable, and includes any deductions authorized under the provisions of section three, article five, chapter twenty-one of this code, except deductions for union or club dues, pension plans, payroll savings plans, charities, stock purchase plans and hospitalization and medical insurance.
(3) Any assignment of earnings and any deduction under said section three, article five, chapter twenty-one of this code shall be revocable by the employee at will at any time, notwithstandingany provision to the contrary.
(4) The priority of multiple assignments of earnings shall be according to the date and time of each such assignment.