syntax_data: {"ast_node_type":"other","tokens":[{"end":52,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // be able to recursively decode a SyntaxContext
context_before:     // Don't try to decode data while holding the lock, since we need to
context_after:     let (parent, expn_id, transparency) = decode_data(d, raw_id);