old_contents: # -*- coding: utf-8 -*-
  ##############################################################################
  # For copyright and license notices, see __openerp__.py file in module root
  # directory
  ##############################################################################
  from openerp import models, api
  
  
  class invoice(models.Model):
      _inherit = 'account.invoice'
  
      @api.multi
      def clean_internal_number(self):
          # We also clean reference for compatibility with argentinian loc
          self.write({'move_name': False, 'afip_document_number': False})
  
new_contents: # -*- coding: utf-8 -*-
  ##############################################################################
  # For copyright and license notices, see __openerp__.py file in module root
  # directory
  ##############################################################################
  from openerp import models, api
  
  
  class invoice(models.Model):
      _inherit = 'account.invoice'
  
      @api.multi
      def clean_internal_number(self):
          # We also clean reference for compatibility with argentinian loc
          self.write({'move_name': False, 'document_number': False})
  
subject: FIX clean document number