syntax_data: {"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":"hi:"}]}
source_snippet:             hi: BytePos(self.lo.debug_strict_add(len)),
context_before:             lo: BytePos(self.lo),
context_after:             ctxt: SyntaxContext::from_u16(self.ctxt),