How to get wizard id in onchange method? Do you know some trick to do this? I searched for examples in standard modules but without answer.

class some_wizard(osv.osv_memory):    
     _columns = {
        'some_string': fields.char('Some string', size=256),
    }

def default_get(self, cr, uid, fields, context=None):
    ret = super(some_wizard,self).default_get(cr, uid, fields, context=context)
    print 'default_get', ret, context
    # 'default_get'
    # ret: []
    # context: {'lang': 'en_US', 'tz': 'Europe/Brussels', 'uid': 1}
    return ret

def onchange_some_string(self, cr, uid, ids, some_string=None, context=None):
    print ids, context
    # context : {'lang': 'en_US', 'tz': 'Europe/Brussels', 'uid': 1}
    # ids: []
    return {}

<record id="" model="ir.ui.view">
            <field name="name"></field>
            <field name="model"></field>
            <field name="arch" type="xml">
                <form string="some_string" version="7.0">
                    <group>
                        <field name="some_string" on_change="onchange_some_string(some_string,context)" />
                    </group>
                    <footer>
                        or
                        <button string="Cancel" class="oe_link" special="cancel" />
                    </footer>
                </form>
            </field>
        </record>