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I came accross following defs, what are the meaning of these two sharp sign toward the end of define macro statement?

where:
SW_DEFINE_HANDLE - macro name
object - parameters passed to macro
object##_T - ##???

#define SW_DEFINE_HANDLE(object) typedef struct object##_T* object;

Now I see usages like:

SW_DEFINE_HANDLE(Instance)
SW_DEFINE_HANDLE(lDevice)
SW_DEFINE_HANDLE(Queue)

Thanks.,