Typo: 'mode' should be a key rather than value.

[whitish]

If you change it to key you will see significantly slower conversion. Looks like this typo comes from the original class though.

https://github.com/cthorey/CS231/blob/11f0521c4f7865a0005f21bb24ec29c8b00c2712/assignment2/cs231n/classifiers/cnn.py#L143

Should be:

    bn_param['mode'] = mode