How to use the pkgconfig.pkgconfig function in pkgconfig

from setuptools import setup, find_packages, Extension
from pkgconfig import pkgconfig
from subprocess import PIPE,Popen
import os

VERSION = 2.0

deps = pkgconfig("cairo")

sources = ["src/%s" % f for f in ["config.cpp","configs.cpp","vector.cpp","object.cpp","hexagon.cpp","game.cpp","pymodule.cpp","wireframe.cpp","draw.cpp"]]

if 'extra_compile_args' not in deps:
    deps['extra_compile_args'] = []
deps['extra_compile_args'].append("-std=c++11")

extension_mod = Extension("spacefortress/core/_spacefortress", sources, **deps)

descr_file = os.path.join(os.path.dirname(__file__), 'README.rst')

setup(
    name = "spacefortress",
    version = '%s' % VERSION,
    description='A python wrapper to c-spacefortress',
    long_description=open(descr_file).read(),