the developer point of view, P can be seen as a standalone library containing all important quantities needed to perform quantum chemistry calculations, both involving wave function theory, through the determinant driven algorithms, and DFT methods, thanks to the presence of a quadrature grid for numerical integrations and basic functionals. ese appealing features are made more concrete thanks to the organization of P in terms of core modules and plugins (see Sec. VII C) together with its programming language (see Sec. VII B), which naturally creates a very modular environment for the programmer.