I have nested dictionary

```
default=time.time()
a={"key":{"key_value":"value", "time": default}}

```

Is it possible that time will change automatically, when I change dictionary?

For example,

```
a
Out[40]:
{'key': {'key_value': 'value', 'time': 1516968395.7678363}}

```

When I change key\_value:

```
a["key"]["key_value"]="value2"

```

It still gives me the same time, but I need updated current time

```
a
Out[44]:
{'key': {'key_value': 'value2', 'time': 1516968395.7678363}}

```