syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"$($("}]}
source_snippet:      $($( #[$attr:meta] )* $opt:ident : $t:ty = (
context_before:     ($struct_name:ident, $tmod_enum_name:ident, $stat:ident, $optmod:ident, $prefix:expr, $outputname:expr,
context_after:         $init:expr,