The posted article is a Rust implementation. The original implementation appears to be here:

https://tfhe.github.io/tfhe/

"TFHE: Fast Fully Homomorphic Encryption over the Torus"

"This library is the original version of TFHE that implements the base arithmetic and functionalities (bootstrapped and leveled)."

"TFHE is an open-source library for fully homomorphic encryption, distributed under the terms of the Apache 2.0 license."

Edit: Although actually that page links to Concrete, a set of Rust crates for FHE. The submitted link is part of the Concrete project.

https://github.com/zama-ai/concrete