n := n.(*ir.SelectStmt)
		walkSelect(n)
		return n

	case ir.OSWITCH:
		n := n.(*ir.SwitchStmt)
		walkSwitch(n)
		return n

	case ir.ORANGE:
		n := n.(*ir.RangeStmt)
		return walkRange(n)
	}

	// No return! Each case must return (or panic),
	// to avoid confusion about what gets returned
	// in the presence of type assertions.
}

func walkStmtList(s []ir.Node) {
	for i := range s {