How do I use rx with datetime?

Since this works:

import pandas as pd
import param

from param import rx
URL = 'https://datasets.holoviz.org/penguins/v1/penguins.csv'
url = rx(URL)
df = rx(pd.read_csv)(url)
display(df)

url.rx.value = 'https://datasets.holoviz.org/gapminders/v1/gapminders.csv'

I expected:

import datetime
import param
from param import rx

tz = rx("US/Eastern")
dt = rx(datetime.datetime.now)(tz)
display(dt)

tz.rx.value = "US/Western"

This to work too, but I don’t think it changes.