text: from django.contrib.auth.models import User
  from django.db import models
  
  
  class GoogleSignIn(models.Model):
      """Credentials linking a user to a Google ID."""
      google_id = models.CharField(unique=True, max_length=50)
      user = models.OneToOneField(User)
  
      def __unicode__(self):
          return "username={}, id={}".format(self.user.username,
                                             self.google_id)
  