'get existing info'

def get_existing(self):

    if self.bridge_domain_id:
        if (self.bind_vlan_id or self.l2_sub_interface):
            self.existing['bridge_domain_id'] = self.bridge_domain_id
            self.existing['bind_vlan_list'] = bitmap_to_vlan_list(self.vap_info.get('vlanList'))
            self.existing['bind_intf_list'] = self.vap_info.get('intfList')
    if (self.encapsulation and self.l2_sub_interface):
        self.existing['l2_sub_interface'] = self.l2_sub_interface
        self.existing['encapsulation'] = self.l2sub_info.get('flowType')
        if (self.existing['encapsulation'] == 'dot1q'):
            self.existing['ce_vid'] = bitmap_to_vlan_list(self.l2sub_info.get('dot1qVids'))
        if (self.existing['encapsulation'] == 'qinq'):
            self.existing['ce_vid'] = bitmap_to_vlan_list(self.l2sub_info.get('ceVids'))
            self.existing['pe_vid'] = self.l2sub_info.get('peVlanId')
