Warning: this way of using the CLI is deprecated. Use 'dafny --help' to see help for the new Dafny CLI format
inheritreqs0.dfy(19,13): Error: a precondition for this call could not be proved
inheritreqs0.dfy[Impl](6,17): Related location: this is the precondition that could not be proved

Dafny program verifier finished with 0 verified, 1 error
