checking the pred_masks against COCO classes of interest

[monacv]

How can I check to see if the pred_masks is false for a given COCO class (e.g. bicycle)?

(Pdb) instances.pred_masks
tensor([[[False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         ...,
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False]],

        [[False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         ...,
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False],
         [False, False, False,  ..., False, False, False]]], device='cuda:0')
(Pdb) torch.all(instances.pred_masks == False)
tensor(False, device='cuda:0')

From the above it shows it is True for some classes, right? How can I check if it is true for a class name of my own interest?

I also have this dimension and am not exactly sure what it represents:

(Pdb) instances.pred_masks.shape
torch.Size([2, 414, 640])