Traceback (most recent call last):

  File "D:/untitled/python/7_keras.py", line 2, in <module>

    from keras.models import Sequential

  File "C:\Users\Administrator\AppData\Roaming\Python\Python27\site-packages\keras\__init__.py", line 3, in <module>

    from . import utils

  File "C:\Users\Administrator\AppData\Roaming\Python\Python27\site-packages\keras\utils\__init__.py", line 6, in <module>

    from . import conv_utils

  File "C:\Users\Administrator\AppData\Roaming\Python\Python27\site-packages\keras\utils\conv_utils.py", line 9, in <module>

    from .. import backend as K

  File "C:\Users\Administrator\AppData\Roaming\Python\Python27\site-packages\keras\backend\__init__.py", line 44, in <module>

    assert _image_data_format in {'channels_last', 'channels_first'}

AssertionError