packages discoverer

[jak]

Sometimes, wandering around the web, I find some example of python code
that uses some class or function that I don't know and that I would like
to try. I copy the code locally and when I try to run it, I find that
the package containing the class/function is not installed on my pc, so
I go back to the web to search for it with the search engine. The
question is: is there a command or an easy way to find out the name of
the package that contains the class/function of my interest?

Thank you in advance.