Function swap_ex 

pub unsafe fn swap_ex(
    handle: cublasHandle_t,
    n: c_int,
    x: CUdeviceptr,
    x_type: cudaDataType,
    incx: c_int,
    y: CUdeviceptr,
    y_type: cudaDataType,
    incy: c_int,
) -> Result<(), GpuError>