'Internal method that returns a dataframe containing history bars
of minute frequency for the given sids.'

def _get_history_minute_window(self, assets, end_dt, bar_count, field_to_use):

    try:
        minutes_for_window = self.trading_calendar.minutes_window(end_dt, (- bar_count))
    except KeyError:
        self._handle_minute_history_out_of_bounds(bar_count)
    if (minutes_for_window[0] < self._first_trading_minute):
        self._handle_minute_history_out_of_bounds(bar_count)
    asset_minute_data = self._get_minute_window_data(assets, field_to_use, minutes_for_window)
    return pd.DataFrame(asset_minute_data, index=minutes_for_window, columns=assets)
