code: async def register_user(self, password, **kwds):
          
          # so make one
          user = await self._create_remote_user(password=password, **kwds)
          # if there is no pk field
          if not 'pk' in user:
              # make sure the user has a pk field
              user['pk'] = user['id']
  
          # the query to find a matching query
          match_query = self.model.user == user['id']
  
          # if the user has already been registered
          if self.model.select().where(match_query).count() > 0:
              # yell loudly
              raise RuntimeError('The user is already registered.')
  
          # create an entry in the user password table
          password = self.model(user=user['id'], password=password)
  
          # save it to the database
          password.save()
  
          # return a dictionary with the user we created and a session token for later use
          return {
              'user': user,
              'sessionToken': self._user_session_token(user)
          }
docs: This function is used to provide a sessionToken for later requests.
  
              Args:
                  uid (str): The