(a) When a person who is a resident of the District of Columbia is out of the District or has absconded or concealed himself at the time a cause of action accrues against him, the period limited for the bringing of the action does not begin to run until he comes into the District or while he is so absconded or concealed.
(b) When such a person absconds or conceals himself after the cause of action accrues, the time of his absence or concealment may not be computed as a part of the period within which the action must be brought.