// description of your code here

    public void dumpMapOfMap(Map map) {
        Set s = map.entrySet();
        Iterator sit = s.iterator();
        boolean isFirst = true;

        while (sit.hasNext()) {
            Map.Entry elem = (Map.Entry)sit.next();
            String key = (String)elem.getKey();
            Object value = elem.getValue();

            if (value instanceof String) {
                // recursivity stop condition
                System.out.print(key);
                System.out.print(" : ");
                System.out.println(value);
            } else {
                if (!isFirst) {
                    System.out.println("");
                } else {
                    isFirst = false;
                }
                System.out.println(key);
                Map valueMap = (Map)elem.getValue();
                dumpMapOfMap(valueMap);
            }
        }
    }

require 'enumerator'

ary = [ 1, 2, 3, 4 ]

# iterate over two elements at a time
ary.each_slice(2) { |a,b| p [a, b] }

# iterate over every pair of consecutive pair of numbers
ary.each_cons(2) { |a, b| p [a, b] }

# An Enumerable::Enumerator object can be created as well,
# that mixes in Enumerable, for further processing:
ary.enum_for(:each_cons, 2).map { |a,b| a + b } # => [3, 5, 7]