def subset_of_df(df, row_names=None, col_names=None):
    """
    
    :param df: pd.DataFrame; DataFrame to be subsetted
    :param row_names: list(); List of the rows to include in subset
    :param col_names: col_names; list(); List of the columns to include in subset
    :return: df; pd.DataFrame: Subset of original DataFrame
    """
    subset_df = df[col_names].loc[row_names]
    return subset_df