I want in res.partner model make onchange event on field parent_id. this field already have onchange event by old api, so i changed it`s value on XML to on_change=1 and added .py code

@api.onchange('parent_id')
def onchange_parent_id(self, parent_id=None):
     old_res = super(res_partner, self).onchange_parent_id(self.parent_id.id)old_res = super(res_partner, self).onchange_parent_id(self.parent_id.id)
     if type(old_res) is dict and old_res.has_key('value'):
         for field, value in old_res.get('value').items():
             if hasattr(self, field):
                 setattr(self, field, value)setattr(self, field, value)
     if self.parent_id:
         self.category_id = self.parent_id.category_id
     return old_res

File "/opt/odoo-vaimada/openerp/addons/base/res/res_partner.py", line 477, in _fields_sync    
context=context).get('value', {})
TypeError: onchange_parent_id() takes at most 2 arguments (6 given)

as i understand it occurrs becouse on create other method (_fields_sync) also calls this onchange_parent_id methot by 'old style'. Maybe someone can advice me how to fix this.

Thanks in advance