A list containing two objects, new and cumulative "new" shows the plot for the new cases/deaths
and "cumulative" shows the plot for the cumulative cases/deaths. If any of them did not get plotted due to lack of prediction or due to the cases
argument, its value will return NULL.
By default, only the plot with new cases is generated.
This is changed with the cases argument.
newThe plotted new cases/deaths. The plots are for daily new confirmed cases and daily new deaths.
cumulativeThe plotted cumulative cases/deaths. The plots are for daily cumulative cases or daily cumulative deaths.