def METHOD_NAME(self):
    if self.purchase_amount:
        for dep in self.depreciation_ids:
            dep.amount_depreciable = self.purchase_amount * dep.base_coeff
        if self.depreciation_ids.mapped("line_ids").filtered(
            lambda l: l.move_type == "depreciated"
        ):
            title = _("Warning!")
            msg = _(
                "Current asset has already been depreciated. Changes upon"
                " its purchase value will not be automatically reflected"
                " upon depreciation lines, which will have to be updated"
                " manually."
            )
            return {"warning": {"title": title, "message": msg}}