Do a conditional import for CudaUnsharpMask

nabu/preproc/double_flatfield_cuda.py

@@ -2,12 +2,12 @@ import numpy as np
 from .double_flatfield import DoubleFlatField
 from ..utils import check_shape
 from ..cuda.utils import get_cuda_context, __has_pycuda__
-from ..misc.unsharp_cuda import CudaUnsharpMask
 
 if __has_pycuda__:
     import pycuda.gpuarray as garray
     import pycuda.cumath as cumath
     from ..cuda.processing import CudaProcessing
+    from ..misc.unsharp_cuda import CudaUnsharpMask
 
 class CudaDoubleFlatField(DoubleFlatField, CudaProcessing):