def available_python_versions(self):
        for py in supported_pythons:
            try:
                check_call([py, '-c', 'import nose'], stdout=PIPE)
                yield py
            except (OSError, CalledProcessError):
                self.unavailable_pythons.append(py)
Get the executable names of available versions of Python on the system.
dataset/ETHPy150Open networkx/networkx/tools/test_pr.py/TestRun.available_python_versions