test case: Expand '{{HOST.HOST}.regsub([0-9]+, \0)}'
expression: '{{HOST.HOST}.regsub([0-9]+, \0)}'
test case: Expand 'ABC{{HOST.HOST}.regsub([0-9]+, \0)}'
expression: 'ABC{{HOST.HOST}.regsub([0-9]+, \0)}'
test case: Expand '{{HOST.HOST}.iregsub([a-z]+, \0)}'
expression: '{{HOST.HOST}.iregsub([a-z]+, \0)}'
test case: Expand '{{HOST.HOST}.fmtnum(2)}'
expression: '{{HOST.HOST}.fmtnum(2)}'
test case: Expand '{{$USERMACRO}.regsub([0-9]+, \0)}'
expression: '{{$USERMACRO}.regsub([0-9]+, \0)}'
test case: Expand '{{$USERMACRO}.iregsub([a-z]+, \0)}'
expression: '{{$USERMACRO}.iregsub([a-z]+, \0)}'
test case: Expand '{{$USERMACRO}.fmtnum(2)}'
expression: '{{$USERMACRO}.fmtnum(2)}'
test case: Expand '{{$USERMACRO}.fmttime(%H:%M:%S)} 1'
macro_value: '1697177104'
expression: '{{$USERMACRO}.fmttime(%H:%M:%S)}'