title: Explanation about hough_line_peaks after using hough_line
body: <p>Could anyone please explain why after using <code>h,theta,d = hough_line(image)</code> which will detect the angles in an image do we have to use this for loop <code>for _, a, d in zip(*hough_line_peaks(h, theta, d)):
          angle.append(a) #angle is a list</code> to add the angles to the list?
  Since the <code>hough_line(image)</code> will store the angles in the theta variable why can't we use it to retrieve the angles and add them to a list? </p>
  
  <p>Here's a snippet of the code to detect angles of lines in an image:</p>
  
  <pre><code>image = imread(file_name)  
  image = np.mean(image, axis=2)  
  
  h, theta, d = hough_line(image)  
  
  angle = []  
  
  for _, a, d in zip(*hough_line_peaks(h, theta, d)):
          angle.append(a)  
  
  angle = [a * 180 / np.pi for a in angle]
  </code></pre>