content: 
  ' The MIT License (MIT)
  
  ' Copyright (c) 2015 Karim Kawambwa
  
  ' Permission is hereby granted, free of charge, to any person obtaining a copy
  ' of this software and associated documentation files (the "Software"), to deal
  ' in the Software without restriction, including without limitation the rights
  ' to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  ' copies of the Software, and to permit persons to whom the Software is
  ' furnished to do so, subject to the following conditions:
  
  ' The above copyright notice and this permission notice shall be included in
  ' all copies or substantial portions of the Software.
  
  ' THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  ' IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  ' FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  ' AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  ' LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  ' OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  ' THE SOFTWARE.
  
  function NavigationManager()
      this = {
          pr___   : { 'don't access directly
              navigationStackIds : []
              navigationStack    : []
          }
      }
      
      this.controllerAtIndex = function(index)
          navStack = m.pr___.navigationStack
          stackCount = navStack.Count()
          if stackCount = 0 then
              return invalid
          end if
          if index < 0 or index >= stackCount then
              print "Index [",index,"] Beyond Bounds of the navigationStack : ", m.pr___.navigationStack.Count()
              return invalid
          end if
          
          return navStack[index]
      end function
      
      this.previousController = function()
          navStack = m.pr___.navigationStack
          stackCount = navStack.Count()
          if stackCount = 0 or stackCount = 1 then return invalid
          
          return navStack[stackCount-2]
      end function
      
      this.currentController = function()
          navStack = m.pr___.navigationStack
          stackCount = navStack.Count()
          if stackCount = 0 then return invalid
          
          return navStack[stackCount-1]
      end function
      
      this.popBack = function()
      end function
      
      this.navigateTo = function(controller, preventHistory = false as Boolean)
          navStack = m.pr___.navigationStack
          navStackIds = m.pr___.navigationStackIds
          
          navStackIds.Push(controller.id)
          navStack.Push(controller)
          
          previousController  = m.previousController()
          currentController   = m.currentController()
          
          if previousController <> invalid then previousController.dispose()
          if currentController <> invalid then currentController.init()
      end function
      
      this.popToInitialController = function()
      end function
      
      return this
  end function