Bug160.dfy(26,18): Error BP5003: A postcondition might not hold on this return path.
Bug160.dfy(27,13): Related location: This is the postcondition that might not hold.
Bug160.dfy(27,29): Related location
Execution trace:
    (0,0): anon0
    (0,0): anon4_Else

Dafny program verifier finished with 2 verified, 1 error
