Dependency and injector

Hi,

I am reading the code at:
https://github.com/Xilinx/brevitas.

dependency and injector is used in the file:
https://github.com/Xilinx/brevitas/blob/master/src/brevitas/inject/__init__.py

I tried to navigate to _dependencies.injector, but I found the package name and information.

is _dependencies.injector the package in python?
or is _dependencies.injector a third party package?
is there any document or tutorial about how to use it?