CoPrefix.dfy(164,2): Error BP5003: A postcondition might not hold on this return path.
CoPrefix.dfy(163,14): Related location: This is the postcondition that might not hold.
Execution trace:
    (0,0): anon0
    (0,0): anon3_Else
CoPrefix.dfy(169,2): Error BP5003: A postcondition might not hold on this return path.
CoPrefix.dfy(168,14): Related location: This is the postcondition that might not hold.
Execution trace:
    (0,0): anon0
    (0,0): anon3_Else
CoPrefix.dfy(176,10): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
    (0,0): anon3_Then
CoPrefix.dfy(205,6): Error: the calculation step between the previous line and this line might not hold
Execution trace:
    (0,0): anon0
    (0,0): anon8_Then
    (0,0): anon10_Then
CoPrefix.dfy(207,6): Error: the calculation step between the previous line and this line might not hold
Execution trace:
    (0,0): anon0
    (0,0): anon8_Then
    (0,0): anon11_Then
CoPrefix.dfy(220,12): Error: prefix-equality limit must be at least 0
Execution trace:
    (0,0): anon0
    (0,0): anon8_Then
    (0,0): anon11_Then
CoPrefix.dfy(63,56): Error: failure to decrease termination measure
Execution trace:
    (0,0): anon0
    (0,0): anon7_Then
    (0,0): anon8_Else
    (0,0): anon9_Then
CoPrefix.dfy(76,55): Error: cannot prove termination; try supplying a decreases clause
Execution trace:
    (0,0): anon0
    (0,0): anon7_Then
    (0,0): anon8_Else
    (0,0): anon9_Then
CoPrefix.dfy(114,0): Error BP5003: A postcondition might not hold on this return path.
CoPrefix.dfy(113,10): Related location: This is the postcondition that might not hold.
CoPrefix.dfy(101,16): Related location
Execution trace:
    (0,0): anon0
    (0,0): anon3_Then
CoPrefix.dfy(138,24): Error: assertion violation
Execution trace:
    (0,0): anon0
    (0,0): anon9_Then
    (0,0): anon10_Then
CoPrefix.dfy(142,24): Error: assertion violation
CoPrefix.dfy(117,22): Related location
Execution trace:
    (0,0): anon0
    (0,0): anon9_Then
    (0,0): anon12_Then
CoPrefix.dfy(151,0): Error BP5003: A postcondition might not hold on this return path.
CoPrefix.dfy(150,10): Related location: This is the postcondition that might not hold.
Execution trace:
    (0,0): anon0
    (0,0): anon3_Else

Dafny program verifier finished with 43 verified, 12 errors