title: IndentationError: unindent does not match any outer indentation level (opencv and python)
body: <p>I'm getting this error:</p>
  
  <pre><code>File "eye_motion_tracking.py", line 17
      _, contours, _= cv2.findContours(skin_ycrcb, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
                                                                                             ^
  IndentationError: unindent does not match any outer indentation level
  </code></pre>
  
  <p>Here is the code:</p>
  
  <pre><code>import cv2
  import numpy as np
  
  cap = cv2.VideoCapture("eye_recording.flv")
  
  while True:
      ret, frame = cap.read()
      if ret is False:
          break
  
      roi = frame[269: 795, 537: 1416]
      rows, cols, _ = roi.shape
      gray_roi = cv2.cvtColor(roi, cv2.COLOR_BGR2GRAY)
      gray_roi = cv2.GaussianBlur(gray_roi, (7, 7), 0)
  
      _, threshold = cv2.threshold(gray_roi, 3, 255, cv2.THRESH_BINARY_INV)
    _, contours, _= cv2.findContours(skin_ycrcb, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)
      contours = sorted(contours, key=lambda x: cv2.contourArea(x), reverse=True)
  
      for cnt in contours:
          (x, y, w, h) = cv2.boundingRect(cnt)
  
          #cv2.drawContours(roi, [cnt], -1, (0, 0, 255), 3)
          cv2.rectangle(roi, (x, y), (x + w, y + h), (255, 0, 0), 2)
          cv2.line(roi, (x + int(w/2), 0), (x + int(w/2), rows), (0, 255, 0), 2)
          cv2.line(roi, (0, y + int(h/2)), (cols, y + int(h/2)), (0, 255, 0), 2)
          break
  
      cv2.imshow("Threshold", threshold)
      cv2.imshow("gray roi", gray_roi)
      cv2.imshow("Roi", roi)
      key = cv2.waitKey(30)
      if key == 27:
          break
  
  cv2.destroyAllWindows()
  </code></pre>