def _mesh_headings_to_class(mesh_headings):
    """Extract a class from the mesh headings.

    We take the first mesh heading and extract it to use as a class.

    Args:
        mesh_headings (list): The list containing all the mesh headings.

    Returns:
        str: The class value.
    """
    return mesh_headings[0].split('/')[0].split(' ')[0].replace('*', '').lower(
        )
