An employee who is entitled to take paid or unpaid leave (including family, medical, sick, annual, personal, or similar leave) from employment, pursuant to federal, state, or local law, a collective bargaining agreement, or an employment benefits program or plan, may elect to substitute any period of such leave for an equivalent period of leave provided under Section 9-3202. If an employee exercises his or her rights to substitute other categories of leave time under this Section, the amount of such substituted leave taken by said employee shall be subtracted from the leave time said employee is entitled to under Section 9-3202.