def available_events
      state = current_state
      ret = {}
      while(state) do
        ret = state.class.specification.events.merge(ret)
        state = state.parent_state
      end
      ret
    end
def available_events
      state = current_state
      ret = {}
      while(state) do
        ret = state.class.specification.events.merge(ret)
        state = state.parent_state
      end
      ret
    end
All events the current state will respond to