only do a cythonize of pyx if cython is installed
only do a cythonize of pyx if cython is installed

chadmv/plow,chadmv/plow,chadmv/plow,chadmv/plow,Br3nda/plow,chadmv/plow,chadmv/plow,Br3nda/plow,Br3nda/plow,Br3nda/plow,chadmv/plow,Br3nda/plow