result = dict() for key in d: val = d[key] if val not in result: result[val]=[key] else: result[val].append(key) An inverted dictionary, where the keys and values of the original dictionary are swapped. A sorted dictionary, where the values of the original dictionary are sorted alphabetically. A regular dictionary, which is exactly the same as the original dictionary." A counter dictionary, where the occurrences of elements in a sequence are counted