pyobjus nameerror: name 'build_ext' is not defined during installation

Question

I'm trying to install pyobjus but I still geting error:

ERROR: Command errored out with exit status 1:
 command: /root/anaconda3/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-lm35sz6r/pyobjus/setup.py'"'"'; _file__='"'"'/tmp/pip-install-lm35sz6r/pyobjus/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file_);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, _file_, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-install-lm35sz6r/pyobjus/pip-egg-info
     cwd: /tmp/pip-install-lm35sz6r/pyobjus/
Complete output (5 lines):
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/tmp/pip-install-lm35sz6r/pyobjus/setup.py", line 58, in <module>
    cmdclass={'build_ext': build_ext},
NameError: name 'build_ext' is not defined

I tried many things to solve that like installing pyobjus and cython from different sources but nothing works. Is there any other way to solve that? Or any alternatives for autoclass function from pyobjus? Many thanks.