code: def find_tag_by_name(repo, tag_name, safe=True):
      
      tagfmt = 'tags/{ref}'.format(ref=tag_name)
  
      try:
          ref = repo.get_git_ref(tagfmt)
          if ref and ref.ref:
              return ref
      except github.UnknownObjectException:
          if not safe:
              raise
  
      return None
docs: Find tag by name in a github Repository
  
      Parameters
      ----------
      repo: :class:`github.Repository` instance
  
      tag_name: str
          Short name of tag (not a fully qualified ref).
  
      safe: bool, optional
          Defaults to `True`. When `True`, `None` is returned on failure. When
          `False`, an exception will be raised upon failure.
  
      Returns
      -------
      gh : :class:`github.GitRef` instance or `None`
  
      Raises
      ------
      github.UnknownObjectException
          If git tag name does not exist in repo.