function differentSymbolsNaive(str) {
    str = (
        typeof str === 'string' && str ||
        typeof str === 'number' && `${str}` ||
        ''
    );
    return new Set([...str]).size;
}



/**
* Test Suite 
*/
describe('differentSymbolsNaive()', () => {
    it('returns count of unique characters', () => {
        // arrange
        const str = 'cabca';
        const result = differentSymbolsNaive(str);
        console.log("result: ", result);
        expect(result).toBe(3);
    });
    
    it('returns count of unique digits if input is a number', () => {
        const num = '112233334';
        const result = differentSymbolsNaive(num);
        console.log("result: ", result);
        expect(result).toBe(4);
    });
    
    it('returns 0 if input is null or undefined', () => {
        const val = null;
        const result = differentSymbolsNaive(val);
        console.log("result: ", result);
        expect(result).toBe(0);
    });
    
});