'Request a change to a user\'s email.
Implicitly saves the pending email change record.
Arguments:
email (unicode): The proposed new email for the user.
Returns:
unicode: The activation code to confirm the change.'

def request_change(self, email):

    self.new_email = email
    self.activation_key = uuid.uuid4().hex
    self.save()
    return self.activation_key
