dropMissingValues(columnNames) {
        const cols =
            columnNames && columnNames.length > 0
                ? columnNames
                : this[__columns__];

        return this.filter((row) => {
            for (const col of cols) {
                if ([NaN, undefined, null].includes(row.get(col))) {
                    return false;
                }
            }
            return true;
        });
    }
Return a DataFrame without rows containing missing values (undefined, NaN, null).
@param {Array} columnNames The columns to consider. All columns are considered by default.
@returns {DataFrame} A DataFrame without rows containing missing values.
@example
df.dropMissingValues(['id', 'name'])