syntax_data: {"ast_node_type":"other","tokens":[{"end":53,"kind":"keyword","start":0,"text":"for"}]}
source_snippet:                 for field_pat in subpatterns.iter() {
context_before:                 print_indented!(self, "subpatterns: [", depth_lvl + 2);
context_after:                     self.print_pat(&field_pat.pattern, depth_lvl + 3);