@classmethod
def export_journal(cls, journal):
    """Returns a Markdown representation of an entire journal."""
    out = []
    year, month = -1, -1
    for e in journal.entries:
        if not e.date.year == year:
            year = e.date.year
            out.append('# ' + str(year))
            out.append('')
        if not e.date.month == month:
            month = e.date.month
            out.append('## ' + e.date.strftime('%B'))
            out.append('')
        out.append(cls.export_entry(e, False))
    result = '\n'.join(out)
    return result
