syntax_data: {"ast_node_type":"other","tokens":[{"end":69,"kind":"keyword","start":0,"text":"Placeholder(placeholder)"}]}
source_snippet:             Placeholder(placeholder) => write!(f, "{placeholder:?}"),
context_before:             Bound(debruijn, var) => crate::debug_bound_var(f, *debruijn, var),
context_after:             Unevaluated(uv) => write!(f, "{uv:?}"),