Validation source_addr without timeout

[kylinsoong]

% ./f5-tmsh-validation.py config/BH-BF2M1-HLW_APP-L2000-1B.com_11.16.160.28.running-config ~/Downloads/1102/02.xlsx
Traceback (most recent call last):
  File "/Users/k.song/src/f5-tmsh-generator/./f5-tmsh-validation.py", line 999, in <module>
    spec_validation_list.append(SpecPersistConfiguration(SPEC_ITEM_PERSIT, device_info[0], device_info[1], device_info[2], bigip_running_config, vs_list_all))
  File "/Users/k.song/src/f5-tmsh-generator/./f5-tmsh-validation.py", line 841, in __init__
    super().__init__(name, hostname, management_ip, software_version, data)
  File "/Users/k.song/src/f5-tmsh-generator/./f5-tmsh-validation.py", line 741, in __init__
    self.parse()
  File "/Users/k.song/src/f5-tmsh-generator/./f5-tmsh-validation.py", line 865, in parse
    validation_results = sepc_persist_configuration_validation(self.data, self.vs_list)
  File "/Users/k.song/src/f5-tmsh-generator/./f5-tmsh-validation.py", line 638, in sepc_persist_configuration_validation
    tmsh_rollback = tmsh.get('tmsh', 'modify.ltm.persist').replace("${replace.persist.type}", "source-addr").replace("${replace.persist.name}", i.name).replace("${replace.persist.timeout}", i.timeout)
TypeError: replace() argument 2 must be str, not None