Uses requireNamespace() to check if a package is already installed and provides options for issuing an error, warning, etc. in case the package is not installed.
check_for_pkg(package, func = stop)
Arguments
package: the name of the package to check for
func: what should this check call if the package is not installed? This can be any function, but stop, warning, skip, etc. are likely candidates (default: stop)
Returns
TRUE if the package is installed, FALSE if it is not (invisibly)