Where is the global instance HomeAssistant documented?

I will need to access the global HomeAssistant instance from pyscript but I cannot find a place where it is documented (or the code part where it is defined).

I need to access the details of entities (notably its label(s)), something I did not find a way to get to other than (hopefully) via HomeAssistant

Here it is! Hass object | Home Assistant Developer Docs