 
   # Private: Used by the disposable.
   off: (eventName, handlerToRemove) ->
-    return if @isDisposed
+    return if @disposed
 
     if oldHandlers = @handlersByEventName[eventName]
       newHandlers = []

  #
  # Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  on: (eventName, handler, unshift=false) ->
    if @isDisposed
      throw new Error("Emitter has been disposed")

    if typeof handler isnt 'function'

# ```
module.exports =
class Emitter
  disposed: false

  ###
  Section: Construction and Destruction
