syntax_data: {"ast_node_type":"function","tokens":[{"end":59,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn encode_byte_symbol(&mut self, byte_sym: ByteSymbol);
context_before:     fn encode_symbol(&mut self, sym: Symbol);
context_after:     fn encode_expn_id(&mut self, expn_id: ExpnId);