     func registerDefaultPresenters()
 
     func viewControllersForRouteBranchIdentifier(branchIdentifier: Identifier) -> [UIViewController]
+    func debugString(msg: String) -> String
     func debug(msg: String)
 }
 

                self.popRouteUsingRouteSegmentsToPop(newRecordedSegmentsToPop, sequenceCompletion: sequenceCompletion, popCompletion: popCompletion)
            case .Failure(_):
                // if popping this segment failed, do not attempt to pop the next one, just fail
                sequenceCompletion(.Failure(RoutingErrors.PresenterNotRegistered(recordedSegment.segmentIdentifier)))
                popCompletion()
            }
        }


        } else {
            let previousSequence: [Any] = updatedRecordedSegments.map { $0.segmentIdentifier }
            self.executeRouteSequence(previousSequence, append: false, routeBranch: defaultRouteBranch, completion: completion)
        }
    }
