def METHOD_NAME(df, as_of=None, dt_col='sample_dt', asof_col='observed_dt'):
    ''' Common use case for selecting the latest rows from a bitemporal dataframe as-of a certain date.
    Parameters
    ----------
    df: ``pd.DataFrame``
        Dataframe with a MultiIndex index
    as_of: ``datetime``
        Return a timeseries with values observed <= this as-of date. By default, the latest observed
        values will be returned.
    dt_col: ``str`` or ``int``
        Name or index of the column in the MultiIndex that is the sample date
    asof_col: ``str`` or ``int``
        Name or index of the column in the MultiIndex that is the observed date
    '''
    if as_of:
        if as_of.tzinfo is None and df.index.get_level_values(asof_col).tz is not None:
            as_of = as_of.replace(tzinfo=mktz())
    return fancy_group_by(df,
                          grouping_level=dt_col,
                          aggregate_level=asof_col,
                          method='last',
                          max_=as_of)