Method unique

src/danfojs-base/shared/utils.ts:360–363

* Returns the unique values in an 1D array * @param arr The array

(arr: ArrayType1D)

     * @param arr The array 
    */
    unique(arr: ArrayType1D): ArrayType1D {
        const uniqueArr = new Set(arr);
        return Array.from(uniqueArr);
    }

    /**
     * Checks if array is 1D