code: def factory(feature):
      
      if feature == 'hog':
          return hog
      elif feature == 'deep':
          return deep
      elif feature == 'gray':
          return gray
      elif feature == 'lab':
          return lab
      elif feature == 'luv':
          return luv
      elif feature == 'hsv':
          return hsv
      elif feature == 'hls':
          return hls
      else:
          return rgb
docs: Factory to choose feature extractor
  
      :param feature: name of the feature
      :return: Feature extractor function