syntax_data: {"ast_node_type":"other","tokens":[{"end":42,"kind":"keyword","start":0,"text":"for"}]}
source_snippet:         for width in NONZERO_BYTE_WIDTHS {
context_before:     fn should_permit_identity_transmutation() {
context_after:             let layout = layout::Tree::<Def, !, !>::nonzero(width);