text: from django.contrib.auth.models import (
      AbstractBaseUser, PermissionsMixin, UserManager)
  from django.core.mail import send_mail
  from django.db import connections, models
  from django.dispatch import receiver
  from django.utils import timezone
  from django.utils.translation import ugettext_lazy as _
  
  
  class User(AbstractBaseUser, PermissionsMixin):
      """Cusomtized version of the default `AbstractUser` from Django.
  
      """
      first_name = models.CharField(_('first name'), max_length=100, blank=True)
      last_name = models.CharField(_('last name'), max_length=100, blank=True)
      email = models.EmailField(_('email address'), blank=True, unique=True)
      is_staff = models.BooleanField(
          _('staff status'), default=False,
          help_text=_('Designates whether the user can log into this admin '
                      'site.'))
      is_active = models.BooleanField(
          _('active'), default=True,
          help_text=_('Designates whether this user should be treated as '
                      'active. Unselect this instead of deleting accounts.'))
      date_joined = models.DateTimeField(_('date joined'), default=timezone.now)
  
      objects = UserManager()
  
      USERNAME_FIELD = 'email'
      REQUIRED_FIELDS = []
  
      class Meta:
          verbose_name = _('user')
          verbose_name_plural = _('users')
  
      def get_full_name(self):
          """
          Returns the first_name plus the last_name, with a space in between.
          """
          full_name = '%s %s' % (self.first_name, self.last_name)
          return full_name.strip()
  
      def get_short_name(self):
          "Returns the short name for the user."
          return self.first_name
  
      def email_user(self, subject, message, from_email=None, **kwargs):
          """
          Sends an email to this User.
          """
          send_mail(subject, message, from_email, [self.email], **kwargs)
  