where(condition) {
        return this.filter(condition);
    }
Filter DataFrame rows.
Alias of .filter()
@param {Function | Object} condition A filter function or a column/value object.
@returns {DataFrame} A new filtered DataFrame.
@example
df.where(row => row.get('column1') >= 3)
df.where({'column2': 5, 'column1': 3}))