Sets the list element at index to value.
For more information on the index argument, see LINDEX.
An error is returned for out of range indexes.
@return
@simple-string-reply
@examples
RPUSH mylist "one"
RPUSH mylist "two"
RPUSH mylist "three"
LSET mylist 0 "four"
LSET mylist -2 "five"
LRANGE mylist 0 -1