syntax_data: {"ast_node_type":"other","tokens":[{"end":87,"kind":"keyword","start":0,"text":"Self::Seq(elts)"}]}
source_snippet:             Self::Seq(elts) => match elts.into_iter().map(|elt| elt.prune(f)).try_fold(
context_before:         match self {
context_after:                 Tree::unit(),