code: def create(cls, sessions=None):
          
          manager = getattr(SMCRequest, '_session_manager')
          if manager is not None:
              return manager
          manager = SessionManager(sessions)
          manager.mount()
          return manager
docs: A session manager will be mounted to the SMCRequest class through
          this classmethod. If there is already an existing SessionManager,
          that is returned instead.
          
          :param list sessions: a list of Session objects
          :rtype: SessionManager