-`plot.CalGR()` and `plot.SimGR()` gain a `log_scale` argument to display flow time series with a logarithmic scale. ([#71](https://gitlab.irstea.fr/HYCAR-Hydro/airgrteaching/-/issues/71))
#### Bug fixes
- bug fixed in `plot.CalGR()` and `plot.SimGR()`. The functions work well when `log_scale = TRUE` to display flow time series with a logarithmic scale. ([#71](https://gitlab.irstea.fr/HYCAR-Hydro/airgrteaching/-/issues/71))