Attribute "formula" is lost when loading bw database with wurst

[TitouanGreffe]

When loading a bw database with wurst, the attribute "formula" of a technosphere (or biosphere) exchange is not retrieved and so only the raw value in the "amount" attribute is kept. Not sure if the concerned functions are add_input_info_for_indigenous_exchanges or rather extract_exchange where attribute 'formula' is not present yet (in extract_database.py).
@cmutel : Would it be possible to fix this issue to be able to keep formulas?

[TitouanGreffe]

I tried to add in extract_exchange function : data["formula"] = proxy.data.get("formula") but then it paste the string of the formula and not parameters in the formula