syntax_data: {"ast_node_type":"function","tokens":[{"end":68,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn span_extend_while_whitespace(&self, span: Span) -> Span {
context_before:     /// span if a `SpanSnippetError` was encountered.
context_after:         self.span_extend_while(span, char::is_whitespace).unwrap_or(span)