Open and return the yaml contents.

def _load_yaml_config(path=None):
    """Open and return the yaml contents."""
    countour_yaml_path = path or find_contour_yaml()

    if countour_yaml_path is None:
        logging.debug("countour.yaml not found.")
        return None

    with open(countour_yaml_path) as yaml_file:
        return yaml_file.read()