'Create a single course vertical of type XBlockFixtureDesc with category `vertical`.
A single course vertical can contain single or multiple video modules.
:param vertical_contents: a list of items for the vertical to contain
:param vertical_index: index for the vertical display name
:return: XBlockFixtureDesc'

def _create_single_vertical(self, vertical_contents, vertical_index):

    xblock_course_vertical = XBlockFixtureDesc('vertical', 'Test    Vertical-{0}'.format(vertical_index))
    for video in vertical_contents:
        xblock_course_vertical.add_children(XBlockFixtureDesc('video', video['display_name'], metadata=video.get('metadata')))
    return xblock_course_vertical
