let input = [[1, 2, [3, 4]], function(a) { return a; }, { "name": "Martin" }, 3, 4, 5, function(a) { return (a + 1)}]
let arr = eval(input);
let results = 0;
let intCounter = 0;
let result = [];
let i = 1;


arr.forEach(element => {

    if ( Array.isArray(element)) {
            let isNested = false;

        for(let i = 0; i < element.length; i++){
            // handle nested
            if(Array.isArray(element[i])){
                isNested = true;
                break;
            }
        }
        if (isNested) {
            var newElement = element.reduce(function(prev, curr) {
                console.log(prev);
                    return prev.concat(curr);
                });
            results.push(newElement);
        } else {
            results.push(newElement);
        }

    } else if ( typeof element == "object") {

        let key = Object.keys(element)[0];
        result.push(key + ": " + element[key]);

    } else if (typeof element == "number") {

        intCounter++;

    } else if (typeof element == "string") {

        //reverse string
        result.push(element.split("").reverse().join(""));
       // console.log( element.split("").reverse().join(""));


    } else if (typeof element == "function") {

        //call function

        result.push(element(42));


    }
});

if(intCounter > 0) {
   result.unshift(intCounter);
}
result =JSON.stringify(result);

console.log(result);