class Man
 {
    constructor(name = "unknown", country = "unknown") {
        this.name = name;
        this.country = country;
    }
}

let man1 = new Man();
//man1.name is "unknown"
//man1.country is "unknown"

let man2 = new Man("Vladimir");
//man2.name is "Vladimir"
//man2.country is "unknown"

let man3 = new Man("Vladimir", "Brazil");
//man3.name is "Vladimir"
//man3.country is "Brazil"

console.log("name1 is", man1.name);
console.log("country1 is", man1.country);

console.log("name2 is", man2.name);
console.log("country2 is", man2.country);

console.log("name2 is", man3.name);
console.log("country3 is", man3.country);