{"ast_node_type":"other","tokens":[{"end":44,"kind":"keyword","start":0,"text":"args:"}]}
        args: Box<[Spanned<Operand<'tcx>>]>,
        /// reused across function calls without duplicating the contents.
        // FIXME(explicit_tail_calls): should we have the span for `become`? is this span accurate? do we need it?