What set of methods does the Single class in the RxJava library provide?

The Single class in RxJava represents a stream that emits exactly one item or an error. The main methods provided by Single:

• subscribe() — subscribing to receive the result or error.
• map() — transforming the emitted value.
• flatMap() — transforming with returning another Single.
• doOnSuccess(), doOnError() — side effects on success or error.
• onErrorReturn(), onErrorResumeNext() — error handling and result replacement.
• zipWith() — combining with another Single.

Example usage:

Single.just("Hello")
    .map { it.length }
    .subscribe({ length -> println("Length: $length") }, { error -> println("Error: $error") })

Single is convenient for operations that return a single result, such as network requests or database reads.