author_lesson           Author a swirl lesson.
bye                     Exit swirl.
info                    Display a list of special commands.
install_course_directory
                        Install a course from a course directory
install_course_dropbox
                        Install a course from a zipped course directory
                        shared on Dropbox
install_course_github   Install a course from a GitHub repository
install_course_google_drive
                        Install a course from a zipped course directory
                        shared on Google Drive
install_course_url      Install a course from a url that points to a
                        zip file
install_course_zip      Install a course from a zipped course folder
install_from_swirl      Install a course from swirl's official list of
                        courses
nxt                     Begin the upcoming question or unit of
                        instruction.
omnitest                Test for a correct expression, a correct value,
                        or both.
play                    Tell swirl to ignore console input for a while.
skip                    Skip the current unit of instruction.
swirl                   An interactive learning environment for R and
                        statistics.
uninstall_course        Uninstall a course
zip_course              Zip a course directory
