Creating a Topojson file

Hello. 

I would like to use a topoJSON file for a map overlay.

I have the GeoJSON file needed, but I am having a hard time finding any good way to convert it to a topojson file.

Does any of you have a method for doing this? I tried the "topojson" module for Python, to that seems to be broken, it seems the Topology() method doesn't exist. I haven't found any working online converters either.