python/roi_data_layer.py
def backward(self, top, propagate_down, bottom):
    """
    This layer does not back propagate
    """
    pass

    This layer does not back propagate
    
This layer does not back propagate
This layer does not back propagate
def backward(self, top, propagate_down, bottom):
    pass
def backward ( self , top , propagate_down , bottom ) : pass
This layer does not back propagate
This layer does not back propagate
"""
    This layer does not back propagate
    """
self
top
propagate_down
bottom