syntax_data: {"ast_node_type":"function","tokens":[{"end":53,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn split_at(self, pos: u32) -> (Span, Span) {
context_before:     /// Splits a span into two composite spans around a certain position.
context_after:         let len = self.hi().0 - self.lo().0;