pub fn every(pattern: &str) -> String {
format!("*/{}", pattern)
}
pub fn nth_occurrence(pattern: &str, occurrence: usize) -> String {
format!("{}#{}", pattern, occurrence)
}
pub fn closest_week_day(pattern: &str) -> String {
format!("{}W", pattern)
}
pub fn last(pattern: &str) -> String {
format!("{}L", pattern)
}
pub fn always() -> String {
"*".to_string()
}