-------------------- t1.bpl --------------------
t1.bpl(23,3): Error BP5001: This assertion might not hold.
Execution trace:
    t1.bpl(16,3): anon0

Boogie program verifier finished with 0 verified, 1 error

-------------------- t2.bpl --------------------
t2.bpl(23,3): Error BP5001: This assertion might not hold.
Execution trace:
    t2.bpl(16,3): anon0

Boogie program verifier finished with 0 verified, 1 error