Used to track which Prompt.matches() handler is active. This is used internally to move the handlers waterfall to the next step.
If true, we're returning from an unexpected interruption and should send the initial turn-0 prompt again.
Timestamp of the last turn.
Options that the prompt was called with.
Number of times the user has interacted with the prompt. The first message sent to the user is turn-0, the users first reply is turn-1, and so forth.