syntax_data: {"ast_node_type":"other","tokens":[{"end":62,"kind":"keyword","start":0,"text":"(None,"}]}
source_snippet:             (None, None) => self.cfg.start_new_block().unit(),
context_before:             (Some(block), None) | (None, Some(block)) => block,
context_after:             (Some(normal_block), Some(exit_block)) => {