Well this seems clear to me
res.update({'cost' : move.price_unit or move.purchase_line_id.price_unit or move.product_id.standard_price })
if we have already a price_unit in the move(line) we must take it
else we take the price_unit from the purchase line - which will be normally evailable
the move.product_id.standard_price is only here as fall back
Well this seems clear to me line_id. price_unit or move.product_ id.standard_ price })
res.update({'cost' : move.price_unit or move.purchase_
if we have already a price_unit in the move(line) we must take it id.standard_ price is only here as fall back
else we take the price_unit from the purchase line - which will be normally evailable
the move.product_