SnapshotableTrees.dfy(71,25): Error BP5002: A precondition for this call might not hold.
SnapshotableTrees.dfy(595,15): Related location: This is the precondition that might not hold.
SnapshotableTrees.dfy(497,18): Related location
Execution trace:
    (0,0): anon0
    (0,0): anon3_Then
SnapshotableTrees.dfy(71,25): Error BP5002: A precondition for this call might not hold.
SnapshotableTrees.dfy(595,15): Related location: This is the precondition that might not hold.
SnapshotableTrees.dfy(494,15): Related location
Execution trace:
    (0,0): anon0
    (0,0): anon3_Then

Dafny program verifier finished with 53 verified, 2 errors
Main iterates on -15
Main iterates on 0
Main iterates on 1
Main iterates on 2
Main iterates on 3
Tree: -45 -15 0 1 2 3 6 9
