docs: def getImageByTag(tag):
      '''Check if an image with a given tag exists. No side-effects. Idempotent.
      Handles ImageNotFound and APIError exceptions, but only reraises APIError.
      '''
      require_str("tag", tag)
  
      image = None
      try:
          image = client.images.get(tag)
          print("Found image", tag, "...")
      except ImageNotFound:
          print("Image", tag, "does not exist ...")
      except APIError as exc:
          eprint("Unhandled error while getting image", tag)
          raise exc
  
      return image