TraitVerify.dfy(21,7): Error: value of expression (of type 'C?<int>') is not known to be an instance of type 'Tr<int>'
TraitVerify.dfy(25,7): Error: value of expression (of type 'A?') is not known to be an instance of type 'Tr<int>'
TraitVerify.dfy(30,7): Error: value of expression (of type 'A?') is not known to be an instance of type 'A', because it might be null

Dafny program verifier finished with 5 verified, 3 errors
