TypeError: _amount_all() takes at least 6 arguments (1 given)

[jorge]

 def _amount_all(self, cr, uid, ids, fieldname, args, context=None):
        """ Return amount total each line
        """
        for rec in self:
            if rec.invoice_id.type not in 'in_refund':
                rec.amount_tax_ret = sum(l.amount_ret for l in rec.tax_line)
                rec.base_ret = sum(l.base for l in rec.tax_line)
            else:
                rec.amount_tax_ret = -sum(l.amount_ret for l in rec.tax_line)
                rec.base_ret = -sum(l.base for l in rec.tax_line)

con la version 8 de odoo