code: def routine_import(self):
          
          for r in routines.__all__:
              file = importlib.import_module('.' + r.lower(), 'andes.routines')
              self.__dict__[r.lower()] = getattr(file, r)(self)
docs: Dynamically import routines as defined in ``routines/__init__.py``.
  
          The command-line argument ``--routine`` is defined in ``__cli__`` in
          each routine file. A routine instance will be stored in the system
          instance with the name being all lower case.
  
          For example, a routine for power flow study should be defined in
          ``routines/pflow.py`` where ``__cli__ = 'pflow'``. The class name
          for the routine should be ``Pflow``. The routine instance will be
          saved to ``PowerSystem.pflow``.
  
          Returns
          -------
          None