docs: def image_needs_pushing(image):
      """Return whether an image needs pushing
  
      Args:
  
      image (str): the `repository:tag` image to be build.
  
      Returns:
  
      True: if image needs to be pushed (not on registry)
      False: if not (already present on registry)
      """
      d = docker_client()
      try:
          d.images.get_registry_data(image)
      except docker.errors.APIError:
          # image not found on registry, needs pushing
          return True
      else:
          return False