Question about the loading of osm data

Hello, thx for your great work of orienternet. I have a question about the loading of osm data. I found that in reader.py, it supports loading OSMData from "from_dict", "from_json" and "from_xml". But the main format of osm.data is "xx.osm.pbf". I wonder the utils functions of openstreetmap is written by yourself or from other resources. Or can you provide a "from_pbf" function in the code.

Thank you very much!