account_bank_voucher_import/model/account_bank_voucher_import.py

# -*- coding: utf-8 -*-
from openerp import models, fields, api,  _


class account_bank_statement_line(models.Model):
    _inherit = 'account.bank.statement.line'

    voucher_id = fields.Many2one('account.voucher', 'Voucher', readonly=True)