USAGE.md

** How does it works ? **

In picking UI a button "Send to shipper" trigger label generation calling send_to_shipper() in models/stock.picking.py

** How to implement my own carrier ? **

Define a method {carrier}_send_shipping() which is called by _send_shipping native method. Make it return a list of dict of this form :

{
    "exact_price": price,
    "tracking_number": 'number'
    "labels": [{
        "package_id": package_id,
        "name": filename,
        "datas": file_content (base64),
        "file_type": extension,
        "tracking_number": package_number
    }]
}