Object.prototype.size = function() {
        return Object.keys(this).filter((key) => typeof this[key] != 'function').length
    }


    testCase1 = {
        its: 'Will',
        be: "size",
        three: "!"
    }

    testCase2 = {
        skip: function(){console.log('haha')},
        this: "will be"
    }

    testCase3 = {
        zero: () => {console.log("empty")}
    }

    console.log(testCase1.size()) // 3
    console.log(testCase2.size()) // 1
    console.log(testCase3.size()) // 0