NAVIT: Enable/Disable OSD Item via dbus using Python

'''
I Have OSD Item in my navit.xml :
<osd name="bino01" enabled="yes" type="button" x="0" y="0" command="" src="/home/bino/.navit/skins/Mineque_003/logo.png" />

Inside binding_dbus.c of navit, there is (line 1595):
{".osd",    "set_attr",          "sv",      "attribute,value",                         "",    "",  request_osd_set_attr},

I try to disabled that osd item using python via dbus. using python

'''

import dbus
bus = dbus.SessionBus()
conn = bus.get_object('org.navit_project.navit','/org/navit_project/navit')
iface = dbus.Interface(conn, dbus_interface='org.navit_project.navit')
iter=iface.attr_iter()

navit=bus.get_object('org.navit_project.navit', conn.get_attr_wi("navit",iter)[1])
iface.attr_iter_destroy(iter)
osd_iface = dbus.Interface(navit, dbus_interface='org.navit_project.navit.osd')

aa=osd_iface.set_attr({"name":dbus.String("bino01",variant_level=1),"enabled":dbus.String("no",variant_level=1)})

'''
Result :
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.UnknownMethod: Method "set_attr" with signature "a{sv}" on interface "org.navit_project.navit.osd" doesn't exist

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Kindly please give me your enlightment to fix this problem

'''