我怎么知道哪个参数在Python中引发异常（使用OpenCV）？

Question

Python（使用OpenCV）会抛出以下TypeError。但我不知道哪个论点会抛出它。我该怎么说？

Traceback (most recent call last):
  File "u.py", line 18, in <module>
    out = unravel2(img,pupil)
  File "/home/chris/code/opencv/iris/support.py", line 57, in unravel2
    cv2.logPolar(img, out, center, cv2.WARP_FILL_OUTLIERS)
TypeError: a float is required

对于背景，这是我的代码：

def unravel2(img, pupil):
  out = np.zeros((max_radius-min_radius,720,3), np.uint8)
  center = (297.5,234.5)
  cv2.logPolar(img, out, center, cv2.WARP_FILL_OUTLIERS)

  return out