Return datetime object from timestamp in Excel serial format.

    Examples
    --------
    >>> datetime_from_timestamp(40237.029999999795)
    datetime.datetime(2010, 2, 28, 0, 43, 11, 999982)

def datetime_from_timestamp(n, epoch=datetime.datetime.fromordinal(693594)):
    """Return datetime object from timestamp in Excel serial format.

    Examples
    --------
    >>> datetime_from_timestamp(40237.029999999795)
    datetime.datetime(2010, 2, 28, 0, 43, 11, 999982)

    """
    return epoch + datetime.timedelta(n)