my_dict = {'a': 1, 'b': 2, 'c': 1, 'd': 3}
value_keys = {}
for key, value in my_dict.items():
value_keys.setdefault(value, key)
print(dict(map(reversed, value_keys.items())))
bXlfZGljdCA9IHsnYSc6IDEsICdiJzogMiwgJ2MnOiAxLCAnZCc6IDN9CnZhbHVlX2tleXMgPSB7fQpmb3Iga2V5LCB2YWx1ZSBpbiBteV9kaWN0Lml0ZW1zKCk6CiAgICB2YWx1ZV9rZXlzLnNldGRlZmF1bHQodmFsdWUsIGtleSkKcHJpbnQoZGljdChtYXAocmV2ZXJzZWQsIHZhbHVlX2tleXMuaXRlbXMoKSkpKQ==