Skeletons.dfy(45,3): Error BP5003: A postcondition might not hold on this return path.
Skeletons.dfy(44,15): Related location: This is the postcondition that might not hold.
Execution trace:
    (0,0): anon0
    Skeletons.dfy[C0](32,5): anon11_LoopHead
    (0,0): anon11_LoopBody
    Skeletons.dfy[C0](32,5): anon12_Else
    (0,0): anon13_Then
    Skeletons.dfy[C0](37,19): anon15_Else
    (0,0): anon10

Dafny program verifier finished with 9 verified, 1 error