def list_(client, file_=None):
    """Get a list of files in the current Creo session that match patterns.

    Args:
        client (obj):
            creopyson Client.
        `file_` (str|list:str, optional):
            File name or List of file names;

    Returns:
        (list:str) List of files.

    """
    data = {}
    if file_:
        if isinstance(file_, (str)):
            data["file"] = file_
        elif isinstance(file_, (list)):
            data["files"] = file_
    return client._creoson_post("file", "list", data, "files")