def METHOD_NAME(
    self, svc, mailchimp_client, sender, recipient
):
    # Try to send the same email twice.
    for _ in range(2):
        svc.send(
            "lms:templates/email/instructor_email_digest/",
            sender,
            recipient,
            template_vars={},
            task_done_key="test_key",
        )
    # It should only have sent the email once.
    assert len(mailchimp_client.messages.send.call_args_list) == 1