'Create XBlockFixtureDesc verticals
:return: a list of XBlockFixtureDesc'

def _add_course_verticals(self):

    xblock_verticals = []
    _contents_of_verticals = self.contents_of_verticals
    if (not _contents_of_verticals):
        _contents_of_verticals = [[{'display_name': 'Video', 'metadata': self.metadata}]]
    for (vertical_index, vertical) in enumerate(_contents_of_verticals):
        xblock_verticals.append(self._create_single_vertical(vertical, vertical_index))
    return xblock_verticals
