EmptySetBug.bpl(33,3): Error BP5001: This assertion might not hold.
Execution trace:
    EmptySetBug.bpl(31,5): anon0
EmptySetBug.bpl(35,3): Error BP5001: This assertion might not hold.
Execution trace:
    EmptySetBug.bpl(31,5): anon0

Boogie program verifier finished with 0 verified, 2 errors