有没有办法按表而不是按行迭代？ API example在行中包含结算日期信息：
Settlement Day,Period,IMBALNGC,Offer Volume Bid Volume,Accepted Offer Vol,Accepted Bid Vol,UAOV,UABV,PAOV,PABV
2014-01-14,1,877.000,52378.500,-53779.500,348.200,-654.374,0.000,0.000,348.200,-654.374
2014-01-14,2,196.000,52598.000,-53559.500,349.601,-310.862,0.000,0.000,316.701,-310.862
2014-01-14,3,-190.000,52575.000,-53283.500,186.183,-2.426,0.000,0.000,162.767,-1.917
2014-01-14,4,-61.000,52576.000,-53454.500,18.000,-24.158,0.000,0.000,18.000,-24.158
但是，如果结算日信息在列中，那么我可以采用类似于API示例的方式：
let firstCol = mrktDepth.Columns|> Seq.head
let settlementDate = firstCol.``Settlement Day``
let acceptedBid = firstCol.``Accepted Bid Vol``
let acceptedOffer = firstCol.``Accepted Offer Vol``