Getting "cannot import name 'ComposeResult' from 'textual.app'

Very new to Textual and Python in general. I’m trying to run and play with some of the examples. Several have the following import line:

from textual.app import App, ComposeResult

When I try running this line, I get the following error:

ImportError: cannot import name ‘ComposeResult’ from ‘textual.app’

I have installed the Textual library successfully and noticed that I can import things from textual but not textual.app. Is that something else? Sorry for the cluelessness but I don’t know enough yet on how to find out for myself. Thank you.