syntax_data: {"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let paren_needed = fn_traits.len() > 1 || traits.len() > 0 || !has_sized_bound;
context_before:         // Insert parenthesis around (Fn(A, B) -> C) if the opaque ty has more than one other trait