Is it ensure, insure, or assure?
v. flexed, flex·ing, flex·es
To contract a muscle.
To move a joint so that the parts it connects approach each other.
1. Faster LEX.
2. A real-time language for dynamic environments.
["FLEX: Towards Flexible Real-Time Programs", K. Lin et al, Computer Langs 16(1):65-79, Jan 1991].
3. An early object-oriented language developed for the FLEX machine by Alan Kay in about 1967. The FLEX language was a simplification of Simula and a predecessor of Smalltalk.