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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def allocate_seg_vlan(self, net_id, is_fw_virt, direc, tenant_id):
 """allocate segmentation ID and VLAN ID. Allocate vlan, seg thereby storing NetID atomically. This saves an extra step to update DB with NetID after allocation. Also may save an extra step after restart, if process crashed after allocation but before updating DB with NetID. Now, since both steps are combined, Vlan/Seg won't be allocated w/o NetID. """

        seg = self.alloc_seg(net_id)
        vlan = 0
        # VLAN allocation is only needed for physical firewall case
        if not is_fw_virt:
            vlan = self.alloc_vlan(net_id)
        # Updating the local cache
        self.update_net_info(tenant_id, direc, vlan, seg)