### 6.3.16 Shifting the elements of a list

The shift command shifts the elements of a list.

- shift takes one mandatory argument and one optional argument:
  - L, a list.
  - Optionally, n, an integer (by default n=−1).
- shift(L) returns the list formed by shifting the elements of L n places to the left if n>0 or −n places to the right if n<0. Elements leaving the list from one side are replaced by zeros on the other side.

#### Examples

shift([0,1,2,3,4])

| ⎡ ⎣ | 0,0,1,2,3 | ⎤ ⎦

shift([0,1,2,3,4],2)

| ⎡ ⎣ | 2,3,4,0,0 | ⎤ ⎦

shift([0,1,2,3,4],-2)

| ⎡ ⎣ | 0,0,0,1,2 | ⎤ ⎦