code: def synchronize(self):
          
          answer = QMessageBox.question(self, _("Synchronize"),
              _("This will synchronize Spyder's path list with "
                      "<b>PYTHONPATH</b> environment variable for current user, "
                      "allowing you to run your Python modules outside Spyder "
                      "without having to configure sys.path. "
                      "<br>Do you want to clear contents of PYTHONPATH before "
                      "adding Spyder's path list?"),
              QMessageBox.Yes | QMessageBox.No | QMessageBox.Cancel)
          if answer == QMessageBox.Cancel:
              return
          elif answer == QMessageBox.Yes:
              remove = True
          else:
              remove = False
          from spyder.utils.environ import (get_user_env, set_user_env,
                                            listdict2envdict)
          env = get_user_env()
          if remove:
              ppath = self.active_pathlist+self.ro_pathlist
          else:
              ppath = env.get('PYTHONPATH', [])
              if not isinstance(ppath, list):
                  ppath = [ppath]
              ppath = [path for path in ppath
                       if path not in (self.active_pathlist+self.ro_pathlist)]
              ppath.extend(self.active_pathlist+self.ro_pathlist)
          env['PYTHONPATH'] = ppath
          set_user_env(listdict2envdict(env), parent=self)
docs: Synchronize Spyder's path list with PYTHONPATH environment variable
          Only apply to: current user, on Windows platforms