def check_columns(df):
    """
    Checks wether dataframe contains the required columns.

    :param df: the data frame with track data.
    :return: whether or not df contains all the required columns.
            required columns: refName, start, end, name, score (is optional)
    :rtype: boolean
    """
    required = ["refName", "start", "end", "name"]
    return all(col in df for col in required)