py_slvs is a Python binding of the 2D/3D geometry constraint solver from a
forked version of
SOLVESPACE.
The fork is based on SOLVESPACE v2.3, with some memory optimization on Linux build. The Python binding is done using SWIG and modeled straight from SOLVESPACE's solver library (see here and here), and is thus considered fairly low level.
The binding is currently used to implement the primiary solver for FreeCAD assembly3 workbench