syntax_data: {"ast_node_type":"other","tokens":[{"end":39,"kind":"keyword","start":0,"text":".rfind(|&(_,"}]}
source_snippet:                 .rfind(|&(_, c)| !f(c))
context_before:                 .char_indices()
context_after:                 .map_or(start, |(i, _)| start - i - 1);