bom_?.py are some python scripts which read a generic xml netlist from eeschema,
and create a bom.

All examples use ky_generic_netlist_reader.py, which is a python utility to read
and parse this generic xml netlist and create the corresponding data
used to build the bom.

You can modify them to build the bom you want.

to use them, you should install python, and run:
python bom_example?.py <netlist name> <bom list netname>

See Eeschema doc, chapter 14 for info about the generic xml netlist format,
and how to run a script from Eeschema to create a customized netlist or BOM.