Returns a new builder for creating observables.

Returns the current read position.

@relates message

Returns the number of pending messages for `receiver`.

Seals the list and returns it.

Returns the priority part from the `category()`.

Returns `true` if the object holds a value (is engaged).

Pushes @p item to the subscriber or buffers them until subscribed.

Starts an `inject` clause. Inject clauses provide a shortcut for sending a message to an actor and then calling `expect` with the same arguments to ch

Generates a `message_id` with given integer value. @relates message_id

Resets this handle but releases the reference count after the current coordinator cycle. @post `!valid()`

Adds `c` to the output buffer.