An m.key.verification.cancel event has been sent or received at any time before the done event, cancelling
the verification request
The verification request is complete.
Normally this means that m.key.verification.done events have been sent and received.
An m.key.verification.ready event has been sent or received, indicating the verification request is accepted.
An m.key.verification.request event has been sent or received
The verification is in flight.
This means that an m.key.verification.start event has been sent or received, choosing a verification method;
however the verification has not yet completed or been cancelled.
Initial state: no event yet exchanged
The current phase of a verification request.