Find dictionary keys with duplicate values

Question

some_dict = {\"firstname\": \"Albert\", \"nickname\": \"Albert\", \"surname\": \"Likins\", \"username\": \"Angel\"}

I would like to return the keys

Answer 1

This method does not require neither external libraries nor an if statement:

    reverse_dic = {}
    for k, v in original_dic.iteritems():
        reverse_dic[v] = reverse_dic.get(v, [])
        reverse_dic[v].append(k)