 `total` and `n`.
        rate  : float, optional
            Manual override for iteration rate.
            If [default: None], uses n/elapsed.
        bar_format  : str, optional
            Specify a custom bar string formatting. May impact performance.
            [default: '{l_bar}{bar}{r_bar}'], where
            l_bar='{desc}: {percentage:3.0f}%|' and
            r_bar='| {n_fmt}/{total_fmt} [{elapsed}<{remaining}, '
              '{rate_fmt}{postfix}]'
            Possible vars: l_bar, bar, r_bar, n, n_fmt, total, total_fmt,
              percentage, elapsed, elapsed_s, ncols, nrows, desc, unit,
              rate, rate_fmt, rate_noinv, rate_noinv_fmt,
              rate_inv, rate_inv_fmt, postfix, unit_divisor,
              remaining, remaining_s, eta.
            Note that a trailing ": " is automatically removed after {desc}
            if the latter is empty.
        postfix  : *, optional
            Similar to `prefix`, but placed at the end
            (e.g. for additional stats).
            Note: postfix is usually a string (not a dict) for this method,
            and will if possible be set to postfix = ', ' + postfix.
            However other types are supported (#382).
        unit_divisor  : float, optional
            [default: 1000], ignored unless `unit_scale` is True.
        initial  : int or float, optional
            The initial counter value [default: 0].
        colour  : str, optional
            Bar colour (e.g. 'green', '#00ff00').

        Returns
        -------
        out  : Formatted meter and stats, ready to display.
        g