code: def urljoin(end_with_slash, *args):
          
          last = args[0]
          for i in args[1:]:
              last = '%s/%s' % (last.strip('/'), i.strip('/'))
  
          if end_with_slash:
              if last[-1] != '/':
                  last += '/'
          return last
docs: >>> HelperURI.urljoin(False, *('http://127.0.0.1:8000', 'dumb_upload'))
          'http://127.0.0.1:8000/dumb_upload'
  
          >>> HelperURI.urljoin(True, *('http://127.0.0.1:8000', 'dumb_upload'))
          'http://127.0.0.1:8000/dumb_upload/'