Python LAYER_PAIR parameter for EXCELLON_WRITER().BuildHolesList()


I am developing a component database and documentation/production files generator tool for KiCad with MSEide+MSEgui:

The code is here:

MSEkicadBOM uses as interface to pcbnew. In there is a “BuildHolesList()” function with the signature “EXCELLON_WRITER self, LAYER_PAIR aLayerPair, bool aGenerateNPTH_list”.
How must the LAYER_PAIR type parameter be defined in Python?
Thanks, Martin

[edit: changed to working link, Joan]