syntax_data: {"ast_node_type":"other","tokens":[{"end":91,"kind":"keyword","start":0,"text":"(fun.span.shrink_to_hi(),"}]}
source_snippet:                     (fun.span.shrink_to_hi(), format!(" as fn({underscored_args}) -> _)")),
context_before:                     (fun.span.shrink_to_lo(), "(".to_owned()),
context_after:                 ],