'imarray' object has no attribute '_imarray__dimension'

Hi, 
I am trying to this code but I get this error : 
```
line 70, in convolve
    if len(mask.shape) != len(self.__dimension):
AttributeError: 'imarray' object has no attribute '_imarray__dimension
```
Knowing that the only change that I made is changing : switching to` scipy.imageio.imread `since `scipy.misc.imread` is deprecated.
Thank you, for helping me.