withHistory method
Returns a new ObservableHistory tracking this Observable, keeping
at most limit recorded values. The caller owns the result and is
responsible for calling ObservableHistory.dispose on it when done —
mirrors select's ownership contract.
Retorna um novo ObservableHistory rastreando este Observable,
mantendo no máximo limit valores registrados. Quem chama é dono do
resultado e é responsável por chamar ObservableHistory.dispose nele
quando terminar — espelha o contrato de posse de select.
Implementation
ObservableHistory<T> withHistory({int limit = 100}) =>
ObservableHistory<T>(this, limit: limit);