title: python vs source code string cannot contain null bytes
body: <p><strong>the source code is:</strong></p>
  
  <pre><code>import numpy
  import cv2
  
  cap=cv2.videoCapture(0)
  while true :
      ret,frame=cap.read()
      gray=cv2.cvtColor(frame,cv2.COLOR_BGR2GRAY)
      cv2.imshow('fram',gray)
      if cv2.waitKey(1)&amp;0xFF==ord('q'):
          break
      cap.release()
      cv2.destroyAllWindows()
  </code></pre>
  
  <p><strong>the error is:  source code string cannot contain null bytes .
  referece to import cv2.
  what is the solution?</strong></p>