TraitPolymorphism.dfy(56,10): Error: arguments must have the same type (got C1 and T2)
TraitPolymorphism.dfy(58,6): Error: RHS (of type C1) not assignable to LHS (of type T2)
TraitPolymorphism.dfy(64,4): Error: LHS of assignment must denote a mutable variable
3 resolution/type errors detected in TraitPolymorphism.dfy