def usage():
    """ print usage info """
    print('usage: mnnconvert [-h]')
    print('    [--framework {TF,CAFFE,ONNX,TFLITE,MNN}')
    print('    [--modelFile MODELFILE]')
    print('    [--prototxt PROTOTXT]')
    print('    [--MNNModel MNNMODEL]')
    print('    [--fp16 {True,False}]')
