def METHOD_NAME(data, days, default = 0):
    """
    Given an iterable of (datestr, value) extending up to `days`
    in the past, pad it with entries containing the `default` value
    so it actually spans all days between now and `days` ago.
    """
    return sorted(dict(
        [((datetime.datetime.now() -
            datetime.timedelta(days=d)).strftime('%Y-%m-%d'), default)
        for d in range(days)] + list(data)).items())