code: def visit_slice(self, node, parent):
          
          newnode = nodes.Slice(parent=parent)
          newnode.postinit(
              _visit_or_none(node, "lower", self, newnode),
              _visit_or_none(node, "upper", self, newnode),
              _visit_or_none(node, "step", self, newnode),
          )
          return newnode
docs: visit a Slice node by returning a fresh instance of it