code: function(list, start, end, value) {
              if (list && isArray(list.value)) {
                  start = evalIndex(list, start, 1);
                  end   = evalIndex(list, end, start + 2) - start;
  
                  var copy = list.value.slice();
                  value // jshint expr: true
                      ? copy.splice(start, end, value)
                      : copy.splice(start, end);
                  return newLessList(copy, list.type);
              }
          }
docs: ....................................................