> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/sidef-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/sidef-lang/programming_tasks/s/singly-linked-list/element_definition.md).

# Element definition

```ruby
var node = Hash(
    data => 'say what',
    next => foo_node,
)
 
node{:next} = bar_node   # mutable
```