How to install pysaxon using pip3?

[mnvx]

I try to install library into my project using next way:

pip3 install -r requirements.txt

My requirements.txt contains:

six
cython
git+https://github.com/ajelenak/pysaxon.git

But installations fails:

Collecting git+https://github.com/ajelenak/pysaxon.git (from -r /var/www/gost/gost/requirements.txt (line 20))
Cloning https://github.com/ajelenak/pysaxon.git to /tmp/pip-zkz6pq1u-build
Complete output from command python setup.py egg_info:
Traceback (most recent call last):
File "", line 1, in
File "/tmp/pip-zkz6pq1u-build/setup.py", line 8, in
from Cython.Build import cythonize
ImportError: No module named 'Cython'

What is wrong?

ps
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