def clean_string_columns(df):
    """Clean string columns in a dataframe."""
    try:
        df.email = df.email.str.lower()
        df.website = df.website.str.lower()
    except AttributeError:
        pass
    str_columns = ["name", "trade_name", "city", "county"]
    for column in str_columns:
        try:
            df[column] = df[column].astype(str).str.title()
            df[column] = df[column].astype(str).str.replace("Llc", "LLC")
            df[column] = df[column].astype(str).str.replace("L.L.C.", "LLC")
            df[column] = df[column].astype(str).str.strip()
        except (AttributeError, KeyError):
            pass
    return df