syntax_data: {"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:                 if let Some(subpattern) = subpattern.as_ref() {
context_before:                 // First, recurse into the subpattern, if any.
context_after:                     // this is the `x @ P` case; have to keep matching against `P` now