sum(columnName) {
        return Number(
            this.df.reduce(
                (p, n) =>
                    isNumber(n.get(columnName))
                        ? p + Number(n.get(columnName))
                        : p,
                0
            )
        );
    }
Compute the sum of a numeric column.
@param {String} columnName The column to evaluate, containing Numbers.
@returns {Number} The sum of the column.
@example
df.stat.sum('column1')