Write a function update_dict2(dict2, key1, key2, value), wheredict2 is a two-level dictionary; key1 is the first-level key; key2 is the second-level key; and value is a value to be stored at dict2[key1][key2]. This function should modify dictionary dict2 so that the following holds:

dict2[key1][key2] == value

The function returns dict2.