syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             //     (mut x, 1) | (2, mut x) if { true } => { ... }
context_before:             // match (30, 2) {
context_after:             //     ...                                 // ^^^^^^^ (this is `arm_block`)