syntax_data: {"ast_node_type":"other","tokens":[{"end":66,"kind":"keyword","start":0,"text":"Ok(None)"}]}
source_snippet:         Ok(None) => return Err(CodegenObligationError::Ambiguity),
context_before:         Ok(Some(selection)) => selection,
context_after:         Err(SelectionError::Unimplemented) => return Err(CodegenObligationError::Unimplemented),