Boogie program verifier finished with 3 verified, 0 errors
LockIncorrect.bpl(17,3): Error BP5001: This assertion might not hold.
Execution trace:
    LockIncorrect.bpl(9,1): start
    LockIncorrect.bpl(14,1): LoopHead

Boogie program verifier finished with 0 verified, 1 error