Usage case:

1. On new requiest an event request fired. This allows to capture request state and deserialize access tokens, session from cookies, etc.
2. On just before the body would be sent, event before-response fired with request and response refs, to serialize security claims into cookies if necessary.
   It is important to schedule for request event handlers like

[interceptSession, rebuildClaims]

while on the before-response the event handlers must be run in opposite order:

[serializeClaims, packSession]

But with current API I can not directly express this with Emittery.
So, I would like to see either

prepend<TName, TData>(eventName:TName, data:TData);

in an Emittery instance, or some flag like:

emitSerial<TName, TData>(name:TName, data:TData, reversed?:boolean):Promise<void>;

in my case I can wrap event handlers registration and postpone actual on calls, until the building of web application will be completed.
But async match of EventEmitter.prependListener and EventEmitter.prependOnceListener may be helpful in some other cases when delayed listeners construction is not possible.