Traceback (most recent call last):


 "<stdin>", line 1, in <module>


 "/usr/local/lib/python3.7/dist-packages/toga_gtk/widgets/webview.py", line 24, in __init__

super().__init__(id=id, style=style, url=url, on_key_down=on_key_down)


 "/usr/local/lib/python3.7/dist-packages/toga/interface/widgets/webview.py", line 29, in __init__

super(WebView, self).__init__(id=id, style=style, url=url, on_key_down=on_key_down, on_webview_load=None)


 "/usr/local/lib/python3.7/dist-packages/toga/interface/widgets/base.py", line 144, in __init__

self.style = CSS()


 "/usr/local/lib/python3.7/dist-packages/toga/interface/widgets/base.py", line 170, in style

self._style = value.bind(self)
AttributeError: 'CSS' object has no attribute 'bind'

Traceback (most recent call last):


 "./tools/train_net.py", line 83, in <module>

roidb = get_training_roidb(imdb)


 "/home/hadi/Software/tensorflow/TEST_FRCN_ROOT/tools/../lib/fast_rcnn/train.py", line 204, in get_training_roidb

imdb.append_flipped_images()


 "/home/hadi/Software/tensorflow/TEST_FRCN_ROOT/tools/../lib/datasets/imdb.py", line 108, in append_flipped_images

boxes = self.roidb[i]['boxes'].copy()


 "/home/hadi/Software/tensorflow/TEST_FRCN_ROOT/tools/../lib/datasets/imdb.py", line 69, in roidb

self._roidb = self.roidb_handler()


 "/home/hadi/Software/tensorflow/TEST_FRCN_ROOT/tools/../lib/datasets/pascal_voc.py", line 107, in gt_roidb

for index in self.image_index]


 "/home/hadi/Software/tensorflow/TEST_FRCN_ROOT/tools/../lib/datasets/pascal_voc.py", line 212, in _load_pascal_annotation

cls = self._class_to_ind[obj.find('name').text.lower().strip()]
AttributeError: 'NoneType' object has no attribute 'lower'
