NonConformingModule.swift

let nonCompliantModule = NonConformingModule()
nonCompliantModule.login(username: "myUsername",
                         password: "myPassword",
                         completion: { (bearerToken, error) in
                                
     print(String(describing: bearerToken))
 })

class NonConformingModule {
    
    func login(username: String,
               password: String,
               completion: ((String?, Error?) -> Void)?) {
        
        let service = NetworkService()
        service.post(scheme: "tandem",
                     host: "login",
                     path: "/login",
                     parameters: ["username": "myUsername",
                                  "password": "myPassword"]) { (response, urlResponse, error) in
                        
                        // We are not going to check errors and URL response status codes, just a shortest path.
                        var networkError: ResponseError? = nil
                        if let error = error {
                            networkError = ResponseError(error: error, response: urlResponse)
                        }
                        let token = response?["bearerToken"] as? String
                        
                        completion?(token, networkError)
        }
    }
}