syntax_data: {"ast_node_type":"variable","tokens":[{"end":51,"kind":"keyword","start":0,"text":"while"}]}
source_snippet:                 while let Some(rhs_child) = child {
context_before:                 let mut child = self.places[rhs].first_child;
context_after:                     let PlaceInfo { ty, proj_elem, next_sibling, .. } = self.places[rhs_child];