Function installMessageHook

installMessageHook(handler, hook): void
Install a message hook for a message handler.
Parameters
- handler: IMessageHandler
  The message handler of interest.
- hook: MessageHook
  The message hook to install.
  
  Notes
  A message hook is invoked before a message is delivered to the handler. If the hook returns false, no other hooks will be invoked and the message will not be delivered to the handler.
  
  The most recently installed message hook is executed first.
  
  If the hook is already installed, this is a no-op.
Returns void
- Defined in index.ts:322