typedef struct SilcAsyncOperationObject *SilcAsyncOperation;

    The asynchronous operation context allocated by silc_async_alloc.
    The layer that implements the asynchronous operation allocates this
    context.  The layer that receives this context can use it to control
    the underlaying asynchronous operation.  It is also possible to use
    a pre-allocated context by using SilcAsyncOperationStruct instead
    SilcAsyncOperation.