'Creates and saves a User with the given email and password.'

def create_user(self, email, date_of_birth, password=None):

    if (not email):
        raise ValueError('Users    must    have    an    email    address')
    user = self.model(email=self.normalize_email(email), date_of_birth=date_of_birth)
    user.set_password(password)
    user.save(using=self._db)
    return user
