如何修复错误:未知类型名称“命名空间”

#ifndef UNO_ACTION_ 
#define UNO_ACTION_
namespace Uno
{
namespace Game
{
    class Game;
}
} // namespace

namespace Uno
{
namespace Action
{
using ::Uno::Game::Game;

class Action
{
public:
    virtual bool isDisposeable() = 0;
    virtual void takeAction(Game* game) = 0;
    virtual ~Action() {}
};

}
}
#endif
#ifndef UNO_ACTION_ 
#define UNO_ACTION_
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