Function syntax_node_to_token_tree 

pub fn syntax_node_to_token_tree<SpanMap>(
    node: &SyntaxNode,
    map: SpanMap,
    span: Span,
    mode: DocCommentDesugarMode,
) -> TopSubtree
where
    SpanMap: SpanMapper,

Converts a syntax tree to a tt::Subtree using the provided span map to populate the subtree’s spans.