subscribe
fun <T : Subscription<D>, D : Subscription.Data> SimpleGraphQLRequest<D>.subscribe( apiCategory: ApiCategory, parserBuilder: () -> T, onSubscriptionEstablished: Consumer<GraphQLResponse<D>>, onSubscription: Consumer<GraphQLResponse<D>>, onSubscriptionCompleted: Action, onFailure: Consumer<ApiException>, variablesSerializer: GraphQLRequest.VariablesSerializer? = null): GraphQLOperation<D>?