version, which is the most recent
version before the function (or other object) was
deprecated.gg_dep(version, msg)gg_dep will give an error, warning, or message,
depending on the difference between the current ggplot2
version and the specified version. If the current major number is greater than
version's major number, or if the current minor
number is more than 1 greater than version's minor
number, give an error.
If the current minor number differs from version's
minor number by one, give a warning.
If the current subminor number differs from
version's subminor number, print a message.