I’m having some trouble provideing a subtype struct with contract-out — anyone know what’s going on here? #lang racket (struct A (a)) (struct B (b) #:super struct:A) (provide (contract-out (struct A ([a any/c])) ; okay (struct (B A) ([a any/c] [b any/c])))) ; error contract-out: cannot determine the number of fields in struct in: B