syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":".with_note(\"`become`"}]}
source_snippet:             .with_note("`become` requires caller and callee to have matching signatures")
context_before:             .struct_span_err(sp, "mismatched signatures")
context_after:             .with_note(format!("caller signature: `{caller_sig}`"))