old_contents: def flip(img, horizontal=False, vertical=False, copy=False):
      """Flip an image in vertical or horizontal direction as specified.
  
      Args:
          img (~numpy.ndarray): An array that gets flipped. This is in CHW
          format. horizontal (bool): flip in horizontal direction
          vertical (bool): flip in vertical direction
          copy (bool): If False, a view of :obj:`img` will be returned.
  
      Returns:
          Transformed :obj:`img` in CHW format.
      """
      if horizontal:
          img = img[:, :, ::-1]
      if vertical:
          img = img[:, ::-1, :]
  
      if copy:
          img = img.copy()
      return img
  
new_contents: def flip(img, horizontal=False, vertical=False, copy=False):
      """Flip an image in vertical or horizontal direction as specified.
  
      Args:
          img (~numpy.ndarray): An array that gets flipped. This is in CHW
              format.
          horizontal (bool): flip in horizontal direction
          vertical (bool): flip in vertical direction
          copy (bool): If False, a view of :obj:`img` will be returned.
  
      Returns:
          Transformed :obj:`img` in CHW format.
      """
      if horizontal:
          img = img[:, :, ::-1]
      if vertical:
          img = img[:, ::-1, :]
  
      if copy:
          img = img.copy()
      return img
  
subject: fix docs