text: from django.contrib import auth
  from django.contrib.auth.base_user import BaseUserManager
  
  
  class UserManager(BaseUserManager):
      use_in_migrations = True
  
      def _create_user(self, email, password, **extra_fields):
          """
          Create and save a user with the given email, and password.
          """
          if not email:
              raise ValueError('The given email must be set')
          email = self.normalize_email(email)
          user = self.model(email=email, **extra_fields)
          user.set_password(password)
          user.save(using=self._db)
          return user
  
      def create_user(self, email=None, password=None, **extra_fields):
          extra_fields.setdefault('is_staff', False)
          extra_fields.setdefault('is_superuser', False)
          return self._create_user(email, password, **extra_fields)
  
      def create_superuser(self, email, password=None, **extra_fields):
          extra_fields.setdefault('is_staff', True)
          extra_fields.setdefault('is_superuser', True)
  
          if extra_fields.get('is_staff') is not True:
              raise ValueError('Superuser must have is_staff=True.')
          if extra_fields.get('is_superuser') is not True:
              raise ValueError('Superuser must have is_superuser=True.')
  
          return self._create_user(email, password, **extra_fields)
  
      def with_perm(self, perm, is_active=True, include_superusers=True, backend=None, obj=None):
          if backend is None:
              backends = auth._get_backends(return_tuples=True)
              if len(backends) == 1:
                  backend, _ = backends[0]
              else:
                  raise ValueError(
                      'You have multiple authentication backends configured and '
                      'therefore must provide the `backend` argument.'
                  )
          elif not isinstance(backend, str):
              raise TypeError(
                  'backend must be a dotted import path string (got %r).'
                  % backend
              )
          else:
              backend = auth.load_backend(backend)
          if hasattr(backend, 'with_perm'):
              return backend.with_perm(
                  perm,
                  is_active=is_active,
                  include_superusers=include_superusers,
                  obj=obj,
              )
          return self.none()
  