syntax_data: {"ast_node_type":"other","tokens":[{"end":13,"kind":"keyword","start":0,"text":"UnsafeFn,"}]}
source_snippet:     UnsafeFn,
context_before:     BuiltinUnsafeBlock,
context_after:     UnsafeBlock { span: Span, hir_id: HirId, used: bool, nested_used_blocks: Vec<NestedUsedBlock> },