git-issue-2211.dfy(17,0): Error: a postcondition could not be proved on this return path
git-issue-2211.dfy(16,10): Related location: this is the postcondition that could not be proved
git-issue-2211.dfy(8,2): Related location: this proposition could not be proved

Dafny program verifier finished with 2 verified, 1 error
