code: def demote(self):
      
      import sys  # Grab a hold of `sys` early since we'll be un-importing our module in this process.
  
      unimported_modules = []
      for name, module in reversed(sorted(sys.modules.items())):
        if self.imported_from_bootstrap(module):
          unimported_modules.append(sys.modules.pop(name))
  
      sys.path[:] = [path for path in sys.path if os.path.realpath(path) != self._realpath]
      sys.path.append(self._sys_path_entry)
  
      return unimported_modules
docs: Demote the bootstrap code to the end of the `sys.path` so it is found last.
  
      :return: The list of un-imported bootstrap modules.
      :rtype: list of :class:`types.ModuleType`