def get_iou(bb1, bb2):
    """
        Gets the Intersection Over Area, aka how much they cross over
        Assumption 1: Each box is a dictionary with the following
            {"x1":top left top corner x coord,"y1": top left top corner y coord,"x2": bottom right corner x coord,"y2":bottomr right corner y coord}
    """
    assert bb1['x1'] < bb1['x2']
    assert bb1['y1'] < bb1['y2']
    assert bb2['x1'] < bb2['x2']
    assert bb2['y1'] < bb2['y2']
    x_left = max(bb1['x1'], bb2['x1'])
    y_top = max(bb1['y1'], bb2['y1'])
    x_right = min(bb1['x2'], bb2['x2'])
    y_bottom = min(bb1['y2'], bb2['y2'])
    if x_right < x_left or y_bottom < y_top:
        return 0.0
    intersection_area = (x_right - x_left) * (y_bottom - y_top)
    bb1_area = (bb1['x2'] - bb1['x1']) * (bb1['y2'] - bb1['y1'])
    bb2_area = (bb2['x2'] - bb2['x1']) * (bb2['y2'] - bb2['y1'])
    iou = intersection_area / float(bb1_area + bb2_area - intersection_area)
    assert iou >= 0.0
    assert iou <= 1.0
    return iou