SET function replaces item at specified index in a list.
If the index is greater than the size of the list, it will raise an error.
When used on a BYTE ARRAY, SET replaces the byte by the byte value. The byte value, signed or not, must be in the range of [-128,255].
Since 2.1, the index can be negative. In this case the effective index is index + size of the LIST or BYTE ARRAY.
Since 2.1, SET can set an element in a nested list. In this case, the index is a list.