git-issue-3804b.dfy(14,9): Error: a postcondition could not be proved on this return path
git-issue-3804b.dfy(16,12): Related location: this is the postcondition that could not be proved
git-issue-3804b.dfy(23,9): Error: a postcondition could not be proved on this return path
git-issue-3804b.dfy(25,12): Related location: this is the postcondition that could not be proved
git-issue-3804b.dfy(40,20): Error: assertion might not hold
git-issue-3804b.dfy(48,21): Error: assertion might not hold

Dafny program verifier finished with 5 verified, 4 errors
