type connStmt struct {
	dc *driverConn
	ds *driverStmt
}

// stmtConnGrabber represents a Tx or Conn that will return the underlying
// driverConn and release function.
type stmtConnGrabber interface {
	// grabConn returns the driverConn and the associated release function
	// that must be called when the operation completes.
	grabConn(context.Context) (*driverConn, releaseConn, error)

	}

	if n := len(dc.openStmt); n != 1 {
		t.Errorf("driverConn num openStmt = %d; want 1", n)
	}
	err = db.Close()
	if err != nil {
		t.Errorf("db Close = %v", err)
	}
	if !dc.closed {
		t.Errorf("after db.Close, driverConn should be closed")
	}
	if n := len(dc.openStmt); n != 0 {
		t.Errorf("driverConn num openStmt = %d; want 0", n)
	}

	err = stmt.Close()