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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def change_email(self, email):
 """ Changes the email address for a user. A user needs to verify this new email address before it becomes active. By storing the new email address in a temporary field -- ``temporary_email`` -- we are able to set this email address after the user has verified it by clicking on the verification URI in the email. This email gets send out by ``send_verification_email``. :param email: The new email address that the user wants to use. """

        self.email_unconfirmed = email

        salt, hash = generate_sha1(self.username)
        self.email_confirmation_key = hash
        self.email_confirmation_key_created = get_datetime_now()
        self.save()

        # Send email for activation
        self.send_confirmation_email()
        
        return self