'get existing info'

def get_existing(self):

    if (not self.config):
        return
    if self.bgp_instance:
        self.existing['bgp_instance'] = self.bgp_instance
    if (self.peer_address and self.peer_enable):
        if self.l2vpn_evpn_exist:
            self.existing['peer_address_enable'] = self.get_peers_enable()
    if (self.peer_group_name and self.peer_enable):
        if self.l2vpn_evpn_exist:
            self.existing['peer_group_enable'] = self.get_peers_group_enable()
    if (self.peer_address and self.advertise_router_type):
        if self.l2vpn_evpn_exist:
            self.existing['peer_address_advertise_type'] = self.get_peers_advertise_type()
    if (self.peer_group_name and self.advertise_router_type):
        if self.l2vpn_evpn_exist:
            self.existing['peer_group_advertise_type'] = self.get_peer_groups_advertise_type()
    if (self.advertise_l2vpn_evpn and self.vpn_name):
        cmd = ('    ipv4-family    vpn-instance    %s' % self.vpn_name)
        exist = is_config_exist(self.config, cmd)
        if exist:
            self.existing['vpn_name'] = self.vpn_name
            l2vpn_cmd = 'advertise    l2vpn    evpn'
            l2vpn_exist = is_config_exist(self.config, l2vpn_cmd)
            if l2vpn_exist:
                self.existing['advertise_l2vpn_evpn'] = 'enable'
            else:
                self.existing['advertise_l2vpn_evpn'] = 'disable'
