def null_value_exists_in_df(df, column_name):
    """
    Get a boolean value as to whether a missing value is included
    in a specific column of the data frame.

    Parameters
    ----------
    df : DataFrame
        Data frame to be checked.
    column_name : str
        The column to be checked.

    Returns
    -------
    result : bool
        If missing values ​​are included, True is set.
    """
    if df[column_name].isnull().any():
        return True
    return False