en_to_es 'cat':'gato'dog':'perroinitial dictionary has no 'mouseen_to_es['mouse''ratonadding 'mouseto the dictionary en_to_es['mouse''raton adding key-value pairs to dictionary is lot easier than it is with lists with lists we needed to append on the end of list with dictionariesbecause there is no inherent orderwe can simply define them with simple expression on the left hand side