Get the parsed description file (a dictionary) from another
       parsed description file.

def _get_description(prev_description):
    """Get the parsed description file (a dictionary) from another
       parsed description file."""
    current_desc_file = os.path.join(utils.get_project_root(),
                                     prev_description['data-source'],
                                     "info.yml")
    if not os.path.isfile(current_desc_file):
        logging.error("You are probably not in the folder of a model, because "
                      "%s is not a file.", current_desc_file)
        sys.exit(-1)
    with open(current_desc_file, 'r') as ymlfile:
        current_description = yaml.load(ymlfile)
    return current_description