Yields relevant closed issues (closed after a given datetime) given a list of issues.

def relevant_issues(issues, after):
    """Yields relevant closed issues (closed after a given datetime) given a list of issues."""
    logging.info('finding relevant issues after {}...'.format(after))
    seen = set()
    for issue in issues:
        if relevent_issue(issue, after) and issue['title'] not in seen:
            seen.add(issue['title'])
            yield issue