new_contents: import yoink.widgets
  import pylab as plt
  
  try:
      from skimage.feature import corner_harris
  except ImportError:
      from yoink.mini_skimage import corner_harris
  
  
  def keyboard_crop(im):
      corners = corner_harris(im)
      lim = {
              'west': corners[:, 1].min()-3,
              'east': corners[:, 1].max()+3,
              'north': corners[:, 0].max()-3,
              'south': corners[:, 0].min()+3,
              }
      limiter = yoink.widgets.KeyboardCrop(im, lim)
  
      limiter.edge_effects['west'] = {'left': -1, 'right': +1}
      limiter.edge_effects['north'] = {'up': +1, 'down': -1}
      limiter.edge_effects['east'] = {'left': +1, 'right': -1}
      limiter.edge_effects['south'] = {'up': -1, 'down': +1}
  
      plt.show()
  
      ylo, xhi, yhi, xlo = limiter.get_edges()
      cropped = im[ylo:yhi, xlo:xhi]
      return cropped
  
subject: add examples.py