>>> from pyroute2 import netns
>>> netns.create("test")
>>> netns.create("test")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/pyroute2/netns/__init__.py", line 162, in create
    os.close(os.open(netnspath, os.O_RDONLY | os.O_CREAT | os.O_EXCL, 0))
OSError: [Errno 17] File exists: '/var/run/netns/test'