Imports NURBS volume(s) from volume mesh (vmesh) file(s).

    :param file: path to a directory containing mesh files or a single mesh file
    :type file: str
    :return: list of NURBS volumes
    :rtype: list
    :raises GeomdlException: an error occurred reading the file

def import_vmesh(file):
    """ Imports NURBS volume(s) from volume mesh (vmesh) file(s).

    :param file: path to a directory containing mesh files or a single mesh file
    :type file: str
    :return: list of NURBS volumes
    :rtype: list
    :raises GeomdlException: an error occurred reading the file
    """
    imported_elements = []
    if os.path.isfile(file):
        imported_elements.append(exch.import_vol_mesh(file))
    elif os.path.isdir(file):
        files = sorted([os.path.join(file, f) for f in os.listdir(file)])
        for f in files:
            imported_elements.append(exch.import_vol_mesh(f))
    else:
        raise exch.GeomdlException("Input is not a file or a directory")
    return imported_elements