Validator validator = new Validator();

        // strings structure check
        
    StringSchema schema = validator.string().required();
    schema.isValid("what does the fox say"); // true
    schema.isValid(""); // false
        
        // numbers structure check
        
    NumberSchema schema = validator.number().required().positive();
    schema.isValid(-10); // false
    schema.isValid(10); // true
        
        // map structure check
        
    MapSchema schema = validator.map();
    Map<String, String> data = new HashMap<>();
    data.put("key", "value");
    schema.isValid(data); // true
        
    schema.sizeof(2);
    schema.isValid(data); // false
    data.put("key2", "value2");
    schema.isValid(data); // true
        
        // shape - allows you to describe validation for Map object values by keys.
        
    Map<String, BaseSchema> schemas = new HashMap<>();
    schemas.put("name", v.string().required());
    schemas.put("age", v.number().positive());
    schema.shape(schemas);

    Map<String, Object> human1 = new HashMap<>();
    human1.put("name", "Kolya");
    human1.put("age", 100);
    schema.isValid(human1); // true

    Map<String, Object> human2 = new HashMap<>();
    human2.put("name", "Maya");
    human2.put("age", null);
    schema.isValid(human2); // true

    Map<String, Object> human3 = new HashMap<>();
    human3.put("name", "");
    human3.put("age", null);
    schema.isValid(human3); // false

    Map<String, Object> human4 = new HashMap<>();
    human4.put("name", "Valya");
    human4.put("age", -5);
    schema.isValid(human4); // false