Iterators.dfy(251,9): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(274,9): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(284,31): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
Iterators.dfy(296,9): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(317,9): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(326,31): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
Iterators.dfy(343,9): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(353,31): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
Iterators.dfy(370,9): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
    (0,0): anon5_Else
    (0,0): anon6_Else
Iterators.dfy(103,21): Error: assertion violation
Execution trace:
    (0,0): anon0
Iterators.dfy(106,13): Error: assertion violation
Execution trace:
    (0,0): anon0
    (0,0): anon4_Then
    (0,0): anon3
Iterators.dfy(177,27): Error: assertion violation
Execution trace:
    (0,0): anon0
    (0,0): anon15_Then
Iterators.dfy(208,6): Error: an assignment to _new is only allowed to shrink the set
Execution trace:
    (0,0): anon0
    Iterators.dfy(197,3): anon16_LoopHead
    (0,0): anon16_LoopBody
    Iterators.dfy(197,3): anon17_Else
    Iterators.dfy(197,3): anon19_Else
    (0,0): anon20_Then
Iterators.dfy(212,20): Error: assertion violation
Execution trace:
    (0,0): anon0
    Iterators.dfy(197,3): anon16_LoopHead
    (0,0): anon16_LoopBody
    Iterators.dfy(197,3): anon17_Else
    Iterators.dfy(197,3): anon19_Else
    (0,0): anon21_Then
Iterators.dfy(40,21): Error BP5002: A precondition for this call might not hold.
Iterators.dfy(4,9): Related location: This is the precondition that might not hold.
Execution trace:
    (0,0): anon0
    (0,0): anon35_Then
    (0,0): anon2
    (0,0): anon36_Then
    (0,0): anon5
    (0,0): anon37_Then
Iterators.dfy(89,13): Error: assertion violation
Execution trace:
    (0,0): anon0
Iterators.dfy(119,15): Error: assertion violation
Execution trace:
    (0,0): anon0
    (0,0): anon3_Else
Iterators.dfy(150,15): Error: assertion violation
Execution trace:
    (0,0): anon0
    (0,0): anon4_Else
Iterators.dfy(155,23): Error BP5002: A precondition for this call might not hold.
Iterators.dfy(125,9): Related location: This is the precondition that might not hold.
Execution trace:
    (0,0): anon0
    (0,0): anon4_Then
    (0,0): anon3
Iterators.dfy(234,20): Error: assertion violation
Execution trace:
    (0,0): anon0
    Iterators.dfy(225,3): anon14_LoopHead
    (0,0): anon14_LoopBody
    Iterators.dfy(225,3): anon15_Else
    Iterators.dfy(225,3): anon18_Else
    (0,0): anon19_Else

Dafny program verifier finished with 65 verified, 20 errors