def _add_tag(tags, label: str) -> bool:
  """Adds the tag to the repeated field of tags.

  Args:
    tags: Repeated field of Tags.
    label: Label of the tag to add.

  Returns:
    True if the tag is added.
  """
  for tag in tags:
    if tag.label == label:
      # Episode already has the tag.
      return False
  tags.add().label = label
  return True