{"ast_node_type":"other","tokens":[{"end":39,"kind":"keyword","start":0,"text":"callee:"}]}
    callee: FnVal<'tcx, M::ExtraFnVal>,
struct EvaluatedCalleeAndArgs<'tcx, M: Machine<'tcx>> {
    args: Vec<FnArg<'tcx, M::Provenance>>,