In the command dev.ctrl_transfer
"The first four parameters are the bmRequestType,bmRequest,wValue and wIndex fields of the standard control transfer structure" ( http://pyusb.sourceforge.net/d.....orial.html
All these args are explained in this page
…USB in a nutshell! Love it!
It's also worth mentioning here that another requirement for usb programming in python is to also install libusb (core usb functions written in c) or openUSB(which itself is based in libusb). You need to install either of these before you try to use pyusb as pyusb is a backend.