Looks at each column, and chooses the feed with the most recent data
        point. Honours the Trump override/failsafe logic.

def most_recent(adf):
        """
        Looks at each column, and chooses the feed with the most recent data
        point. Honours the Trump override/failsafe logic. """
        # just look at the feeds, ignore overrides and failsafes:
        feeds_only = adf[adf.columns[1:-1]]

        # find the feeds with the most recent data...
        feeds_with_data = feeds_only.dropna(how='all')
        selected_feeds = feeds_with_data.T.dropna().index

        # if there aren't any feeds, the first feed will work...
        if len(selected_feeds) == 0:
            pre_final = adf['feed001'] # if there all empyty
                                  # they should all be
                                  # equally empty
        else:
            #if there's one or more, take the highest priority one
            pre_final = adf[selected_feeds[0]]


        # create the final, applying the override and failsafe logic...
        final_df = pd.concat([adf.override_feed000,
                              pre_final,
                              adf.failsafe_feed999], axis=1)
        final_df = final_df.apply(_row_wise_priority, axis=1)
        return final_df