case *Slice:
			do(typ.Elem())

		case *Interface:
			for i := 0; i < typ.NumMethods(); i++ {
				do(typ.Method(i).Type())
			}
		case *Signature:
			tuple := func(tup *Tuple) {
				for i := 0; i < tup.Len(); i++ {
					do(tup.At(i).Type())
				}
			}
			tuple(typ.Params())
			tuple(typ.Results())
		case *Struct:
			for i := 0; i < typ.NumFields(); i++ {
				do(typ.Field(i).Type())
			}
		}

		case *Slice:
			do(typ.Elem())

		case *Interface:
			for i := 0; i < typ.NumMethods(); i++ {
				do(typ.Method(i).Type())
			}
		case *Signature:
			tuple := func(tup *Tuple) {
				for i := 0; i < tup.Len(); i++ {
					do(tup.At(i).Type())
				}
			}
			tuple(typ.Params())
			tuple(typ.Results())
		case *Struct:
			for i := 0; i < typ.NumFields(); i++ {
				do(typ.Field(i).Type())
			}
		}