This file contains the observer interface
Pretty simple, an observer needs to be notified of a change of state from a publisher
This interface assumes that externals can 'attach' themselves to it. In the observer/publisher design pattern implementation found in phabstractic it is built so that both publishers and observers can register listeners/broacasters This can be utilized one-sided, or coupled together in implementation, whichever way is more conducive to the system.
| ObserverInterface | Observer Interface - Identifies Many Different Objects As Notifiable |