syntax_data: {"ast_node_type":"other","tokens":[{"end":74,"kind":"keyword","start":0,"text":"for"}]}
source_snippet:     for arg in fn_abi.args.iter_mut().chain(iter::once(&mut fn_abi.ret)) {
context_before: {
context_after:         softfloat_float_abi(cx.target_spec(), arg);