syntax_data: {"ast_node_type":"other","tokens":[{"end":10,"kind":"keyword","start":0,"text":"$("}]}
source_snippet:         $(
context_before:     ($arch:ident $arch_reg:ident $arch_regclass:ident {
context_after:             $reg:ident: $class:ident $(, $extra_class:ident)* = [$reg_name:literal $(, $alias:literal)*] $(% $filter:ident)?,