Array Methods

Method	Description	Example	Result
`.추가(값)`	Append	`arr.추가(6)`	mutates in place
`.삭제(인덱스)`	Remove at index	`arr.삭제(0)`	returns removed value
`.길이()`	Length	`arr.길이()`	`5`
`.포함(값)`	Contains	`arr.포함(3)`	`참`
`.역순()`	Reverse	`arr.역순()`	new reversed array
`.정렬()`	Sort	`arr.정렬()`	new sorted array
`.합치기(구분자)`	Join to string	`arr.합치기(", ")`	`"1, 2, 3"`