"hello, world" of embedding/extending?

[kj0]

What are the "hello, world" equivalents of embedding and extending
Python (in/with C or C++)?

More generally, where can I find source code didactic examples of
embedding and extending Python?  (I write "didactic" because I'm not
quite at the level yet of being able to read real-world,
multiplatform, distribution-grade applications; rather, I'm interested
in examples ranging from the "hello, world" level of complexity to the
level of a full-blown useful application that someone may write for
personal use, i.e. not intended for wide distribution).

Thanks!

KJ, recovering perloholic