code: def notes_for_version(self, version):
      
      branch_name = self._branch_name(version)
      branch_notes_file = self._branch_notes.get(branch_name, None)
      if branch_notes_file is None:
        raise ValueError(
            'Version {} lives in branch {}, which is not configured in {}.'.format(
              version, branch_name, self._branch_notes))
      return _read_contents(branch_notes_file)
docs: Given the parsed Version of pants, return its release notes.
  
      TODO: This method should parse out the specific version from the resulting file:
        see https://github.com/pantsbuild/pants/issues/1708