ohlc_rse = createReactiveStateEngine(name="ohlc_rse", metrics=[<duration>,<datetime>,<get_posneg(o,c)>,<get_ma3(c)>], dummyTable=ohlc, outputTable=res_ohlc, keyColumn="symbol")----------------------------------------段1

createAsofJoinEngine(name="aje",leftTable=res_quotes,rightTable=res_ohlc,outputTable=result,metrics=[<spread>,<bidasksum>,<posneg>,<ma3>],matchingColumn=`symbol,timeColumn=`datetime,delayedTime=1)----------------------------------------段2

createAsofJoinEngine(name="aje",leftTable=res_quotes,rightTable=res_ohlc,outputTable=result,metrics=<[spread,bidasksum,posneg,ma3]>,matchingColumn=`symbol,timeColumn=`datetime,delayedTime=1)----------------------------------------段3

段1中metrics写成 [<>,<>,<>...]可以运行

段2这样写就不能运行，改为段3的写法又可以运行

为什么？   [<>,<>,<>...]和<[a,b,c]>有啥区别？