.

pyproject.toml

+[build-system]
+requires = ["pygolang[pyx.build]"]

setup.py

@@ -20,7 +20,7 @@
 from setuptools import setup, Extension, Command, find_packages
 from setuptools.command.build_py import build_py as _build_py
 from setuptools.command.build_ext import build_ext as _build_ext
-from Cython.Build import cythonize
+from Cython.Build import cythonize  # XXX -> golang.pyx.build.Extension ?
 from pkg_resources import working_set, EntryPoint
 from distutils.errors import DistutilsExecError
 from subprocess import Popen, PIPE