Derive Macro SinglyLinkedListContainable 

#[derive(SinglyLinkedListContainable)]
{
    // Attributes available to this derive:
    #[sll_node]
}

Derive macro to implement SinglyLinkedListContainable for a struct.

Mark fields that are nodes with #[sll_node]. To support multiple lists, use #[sll_node(tag = MyTag)].