So, how does one create a Lemmy bot?

How does one make a Lemmy bot? A couple of communities I moderate could benefit from a bot to post regular threads based on a template or respond to comments which contain key phrases.

How and where are Lemmy bots hosted? What language are they written in? I have some basic coding experience with Python/Bash/C++, but am not sure where to start when it comes to something like this.

Are there any good step-by-step guides for building a Lemmy bot?