check that end_date occurs after start_date
Examples
if (FALSE) {
start_date <- check_dates(c("1/1/21", "1/2/21", "1/3/21"))
end_date <- check_dates(c("1/7/21", "1/8/21", "1/9/20"))
check_end_after_start_date(start_date, end_date)
}
check that end_date occurs after start_date
if (FALSE) {
start_date <- check_dates(c("1/1/21", "1/2/21", "1/3/21"))
end_date <- check_dates(c("1/7/21", "1/8/21", "1/9/20"))
check_end_after_start_date(start_date, end_date)
}