rename(columnName, replacement) {
        const newColumnNames = this[__columns__].map((column) =>
            column === columnName ? replacement : column
        );
        return this.renameAll(newColumnNames);
    }
Rename a column.
@param {String} columnName The column to rename.
@param {String} replacement The new name for the column.
@returns {DataFrame} A new DataFrame with the new column name.
@example
df.rename('column1', 'columnRenamed')