@classmethod
def get_extent_of_layer(cls, layer):
    """
        Outputs length of the smaller size of the features' bbox
        Returns 0 if the bbox is a Point
        """
    min_extent_features = float(0)
    query = layer.get_extent()
    extent = query['extent']
    if extent:
        x1 = query['extent'][0]
        x2 = query['extent'][2]
        y1 = query['extent'][1]
        y2 = query['extent'][3]
        if x1 != x2 and y1 != y2:
            min_extent_features = min(float(abs(x2 - x1)), float(abs(y2 - y1)))
    return min_extent_features
