@staticmethod
def _get_owner_cover_photo_upload_server(session, group_id, crop_x=0,
    crop_y=0, crop_x2=795, crop_y2=200):
    """
        https://vk.com/dev/photos.getOwnerCoverPhotoUploadServer
        """
    group_id = abs(group_id)
    response = session.fetch('photos.getOwnerCoverPhotoUploadServer',
        group_id=group_id, crop_x=crop_x, crop_y=crop_y, crop_x2=crop_x2,
        crop_y2=crop_y2)
    return response['upload_url']
