Instructions should specify pip3, perhaps

[dougdyer]

I'm not a Python expert, but using Ubuntu 16.04 I found the current instructions apparently start python3 by default. In Linux, "python" start Python v2.x while "python3" starts Python v3.x. Meanwhile, "pip" starts the package manager for Python v2.x, so the instruction to install the onetimepass resulted in python3 being unable to import the module.

To fix, I installed pip3:
sudo apt install python3-pip

Then added onetimepass:
sudo -H pip3 install onetimepass

Then everything worked as expected. Thanks very much for Apache_2fa!