syntax_data: {"ast_node_type":"other","tokens":[{"end":74,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// The return value signifies whether some kind of source is present.
context_before:     /// it is interpreted as an error and the corresponding enum variant is set.
context_after:     pub fn add_external_src<F>(&self, get_src: F) -> bool