Consider I write a module like this:

from osv import fields, osv
from sale_layout import one2many_mod2

class sale_order(osv.osv):

    _inherit = "sale.order"
    _columns = {
        'saleM102_line': one2many_mod2('sale.m102', 'order_id', 'SaleM102'),
    }
sale_order()

OpenERP won't start up, because cannot find sale_layout nor one2many_mod2.

[2013-11-13 10:10:48,390][test] CRITICAL:init:cannot import name one2many_mod2

How can I tell python to look there ?