def get_delete_branch_command(self, branch_name, message=None, author=None):
raise NotImplementedError()<EOL>
Get the command to delete or close a branch in the local repository.

:param branch_name: The name of the branch to create (a string).
:param message: The message to use when closing the branch requires
                a commit (a string, defaults to the string
                "Closing branch NAME").
:param author: Override :attr:`author` (refer to
               :func:`coerce_author()` for details
               on argument handling).
:returns: A list of strings.

This method needs to be implemented by subclasses.