'vlan add bitmap'

def vlan_bitmap_add(self, oldmap, newmap):

    vlan_bit = (['0'] * 1024)
    if (len(newmap) != 1024):
        self.module.fail_json(msg='Error:    New    vlan    bitmap    is    invalid.')
    if ((len(oldmap) != 1024) and (len(oldmap) != 0)):
        self.module.fail_json(msg='Error:    old    vlan    bitmap    is    invalid.')
    if (len(oldmap) == 0):
        return newmap
    for num in range(1024):
        new_tmp = int(newmap[num], 16)
        old_tmp = int(oldmap[num], 16)
        add = ((~ (new_tmp & old_tmp)) & new_tmp)
        vlan_bit[num] = hex(add)[2]
    vlan_xml = ''.join(vlan_bit)
    return vlan_xml
