custom iterator tutorial for R (#4203)
custom iterator tutorial for R (#4203)


larroy/mxnet,xcgoner/dist-mxnet,luoyetx/mxnet,ykim362/mxnet,luoyetx/mxnet,kevinthesun/mxnet,wangyum/mxnet,jermainewang/mxnet,reminisce/mxnet,yajiedesign/mxnet,rahul003/mxnet,jamesliu/mxnet,gautamkmr/incubator-mxnet,Ldpe2G/mxnet,rahul003/mxnet,likelyzhao/mxnet,tlby/mxnet,CodingCat/mxnet,LinkHS/incubator-mxnet,TuSimple/mxnet,LinkHS/incubator-mxnet,jamesliu/mxnet,gautamkmr/incubator-mxnet,ptrendx/mxnet,dmlc/mxnet,hesseltuinhof/mxnet,likelyzhao/mxnet,ShownX/incubator-mxnet,wangyum/mxnet,wangyum/mxnet,likelyzhao/mxnet,navrasio/mxnet,Prasad9/incubator-mxnet,piiswrong/mxnet,thirdwing/mxnet,reminisce/mxnet,apaleyes/mxnet,sergeykolychev/mxnet,yuruofeifei/mxnet,TuSimple/mxnet,saurabh3949/mxnet,thirdwing/mxnet,ForkedReposBak/mxnet,gautamkmr/incubator-mxnet,fullfanta/mxnet,wangyum/mxnet,jiajiechen/mxnet,nicklhy/mxnet,LinkHS/incubator-mxnet,fullfanta/mxnet,indhub/mxnet,DR08/mxnet,fullfanta/mxnet,pluskid/mxnet,yajiedesign/mxnet,CodingCat/mxnet,thirdwing/mxnet,LinkHS/incubator-mxnet,crazy-cat/incubator-mxnet,Prasad9/incubator-mxnet,sxjscience/mxnet,coder-james/mxnet,TuSimple/mxnet,lxn2/mxnet,hpi-xnor/BMXNet,formath/mxnet,coder-james/mxnet,hpi-xnor/BMXNet,wangyum/mxnet,fullfanta/mxnet,tornadomeet/mxnet,yajiedesign/mxnet,leezu/mxnet,kkk669/mxnet,precedenceguo/mxnet,nicklhy/mxnet,ykim362/mxnet,DR08/mxnet,pluskid/mxnet,arank/mxnet,ZihengJiang/mxnet,kevinthesun/mxnet,rishita/mxnet,arank/mxnet,hesseltuinhof/mxnet,LinkHS/incubator-mxnet,apaleyes/mxnet,Prasad9/incubator-mxnet,szha/mxnet,saurabh3949/mxnet,lxn2/mxnet,TuSimple/mxnet,danithaca/mxnet,DickJC123/mxnet,sxjscience/mxnet,crazy-cat/incubator-mxnet,weleen/mxnet,TuSimple/mxnet,coder-james/mxnet,lxn2/mxnet,LinkHS/incubator-mxnet,smolix/incubator-mxnet,stefanhenneking/mxnet,tornadomeet/mxnet,ZihengJiang/mxnet,indhub/mxnet,DickJC123/mxnet,jamesliu/mxnet,nicklhy/mxnet,Ldpe2G/mxnet,yuruofeifei/mxnet,yuruofeifei/mxnet,fullfanta/mxnet,larroy/mxnet,coder-james/mxnet,ZihengJiang/mxnet,jiajiechen/mxnet,mbaijal/incubator-mxnet,tornadomeet/mxnet,hpi-xnor/BMXNet,jennyzhang0215/incubator-mxnet,weleen/mxnet,jennyzhang0215/incubator-mxnet,Northrend/mxnet,CodingCat/mxnet,arikpoz/mxnet,jermainewang/mxnet,smolix/incubator-mxnet,likelyzhao/mxnet,tlby/mxnet,ptrendx/mxnet,sxjscience/mxnet,larroy/mxnet,stefanhenneking/mxnet,coder-james/mxnet,formath/mxnet,mbaijal/incubator-mxnet,crazy-cat/incubator-mxnet,jiajiechen/mxnet,apache/incubator-mxnet,zhreshold/mxnet,zhreshold/mxnet,arikpoz/mxnet,Mega-DatA-Lab/mxnet,yuruofeifei/mxnet,dmlc/mxnet,jermainewang/mxnet,danithaca/mxnet,saurabh3949/mxnet,dmlc/mxnet,navrasio/mxnet,pluskid/mxnet,nicklhy/mxnet,sergeykolychev/mxnet,piiswrong/mxnet,stefanhenneking/mxnet,arank/mxnet,leezu/mxnet,solin319/incubator-mxnet,ShownX/incubator-mxnet,apaleyes/mxnet,smolix/incubator-mxnet,Mega-DatA-Lab/mxnet,smolix/incubator-mxnet,tornadomeet/mxnet,smolix/incubator-mxnet,tornadomeet/mxnet,DickJC123/mxnet,hotpxl/mxnet,eric-haibin-lin/mxnet,piiswrong/mxnet,xcgoner/dist-mxnet,weleen/mxnet,vikingMei/mxnet,arikpoz/mxnet,rishita/mxnet,reminisce/mxnet,Ldpe2G/mxnet,formath/mxnet,Mega-DatA-Lab/mxnet,xcgoner/dist-mxnet,ZihengJiang/mxnet,reminisce/mxnet,reminisce/mxnet,rishita/mxnet,Guneet-Dhillon/mxnet,apaleyes/mxnet,Guneet-Dhillon/mxnet,mbaijal/incubator-mxnet,sxjscience/mxnet,solin319/incubator-mxnet,tlby/mxnet,Ldpe2G/mxnet,luoyetx/mxnet,jermainewang/mxnet,hesseltuinhof/mxnet,sergeykolychev/mxnet,hotpxl/mxnet,reminisce/mxnet,kevinthesun/mxnet,hotpxl/mxnet,szha/mxnet,Prasad9/incubator-mxnet,ZihengJiang/mxnet,coder-james/mxnet,hotpxl/mxnet,vikingMei/mxnet,ptrendx/mxnet,larroy/mxnet,apaleyes/mxnet,gautamkmr/incubator-mxnet,sxjscience/mxnet,EvanzzzZ/mxnet,kevinthesun/mxnet,wangyum/mxnet,Prasad9/incubator-mxnet,dmlc/mxnet,arikpoz/mxnet,crazy-cat/incubator-mxnet,kevinthesun/mxnet,solin319/incubator-mxnet,hotpxl/mxnet,LinkHS/incubator-mxnet,Guneet-Dhillon/mxnet,arikpoz/mxnet,sergeykolychev/mxnet,mbaijal/incubator-mxnet,smolix/incubator-mxnet,ForkedReposBak/mxnet,fullfanta/mxnet,madjam/mxnet,ShownX/incubator-mxnet,arikpoz/mxnet,vikingMei/mxnet,hesseltuinhof/mxnet,likelyzhao/mxnet,larroy/mxnet,lxn2/mxnet,ptrendx/mxnet,kkk669/mxnet,ykim362/mxnet,leezu/mxnet,Guneet-Dhillon/mxnet,weleen/mxnet,dmlc/mxnet,vikingMei/mxnet,yajiedesign/mxnet,pluskid/mxnet,stefanhenneking/mxnet,szha/mxnet,szha/mxnet,sxjscience/mxnet,Northrend/mxnet,jamesliu/mxnet,madjam/mxnet,fullfanta/mxnet,Northrend/mxnet,mbaijal/incubator-mxnet,hpi-xnor/BMXNet,Prasad9/incubator-mxnet,ptrendx/mxnet,ZihengJiang/mxnet,coder-james/mxnet,DR08/mxnet,tlby/mxnet,smolix/incubator-mxnet,Ldpe2G/mxnet,jermainewang/mxnet,jennyzhang0215/incubator-mxnet,tornadomeet/mxnet,madjam/mxnet,hotpxl/mxnet,rishita/mxnet,antoan2/incubator-mxnet,likelyzhao/mxnet,jiajiechen/mxnet,piiswrong/mxnet,yuruofeifei/mxnet,weleen/mxnet,xcgoner/dist-mxnet,kkk669/mxnet,antoan2/incubator-mxnet,EvanzzzZ/mxnet,smolix/incubator-mxnet,tlby/mxnet,yajiedesign/mxnet,hesseltuinhof/mxnet,danithaca/mxnet,fullfanta/mxnet,zhreshold/mxnet,antoan2/incubator-mxnet,EvanzzzZ/mxnet,luoyetx/mxnet,Ldpe2G/mxnet,nicklhy/mxnet,tornadomeet/mxnet,formath/mxnet,likelyzhao/mxnet,tlby/mxnet,ZihengJiang/mxnet,ykim362/mxnet,navrasio/mxnet,jiajiechen/mxnet,jennyzhang0215/incubator-mxnet,precedenceguo/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,yuruofeifei/mxnet,indhub/mxnet,Ldpe2G/mxnet,TuSimple/mxnet,rahul003/mxnet,arikpoz/mxnet,Northrend/mxnet,zhreshold/mxnet,tlby/mxnet,weleen/mxnet,tlby/mxnet,hesseltuinhof/mxnet,jamesliu/mxnet,arank/mxnet,piiswrong/mxnet,Prasad9/incubator-mxnet,jennyzhang0215/incubator-mxnet,thirdwing/mxnet,dmlc/mxnet,hpi-xnor/BMXNet,jiajiechen/mxnet,dmlc/mxnet,stefanhenneking/mxnet,Northrend/mxnet,kkk669/mxnet,LinkHS/incubator-mxnet,eric-haibin-lin/mxnet,jermainewang/mxnet,precedenceguo/mxnet,solin319/incubator-mxnet,thirdwing/mxnet,zhreshold/mxnet,hotpxl/mxnet,vikingMei/mxnet,madjam/mxnet,xcgoner/dist-mxnet,ShownX/incubator-mxnet,ptrendx/mxnet,CodingCat/mxnet,saurabh3949/mxnet,DR08/mxnet,kevinthesun/mxnet,TuSimple/mxnet,tornadomeet/mxnet,jennyzhang0215/incubator-mxnet,saurabh3949/mxnet,TuSimple/mxnet,Northrend/mxnet,EvanzzzZ/mxnet,EvanzzzZ/mxnet,DR08/mxnet,Guneet-Dhillon/mxnet,jermainewang/mxnet,stefanhenneking/mxnet,Northrend/mxnet,xcgoner/dist-mxnet,kkk669/mxnet,rahul003/mxnet,pluskid/mxnet,jennyzhang0215/incubator-mxnet,leezu/mxnet,jermainewang/mxnet,ykim362/mxnet,danithaca/mxnet,navrasio/mxnet,jamesliu/mxnet,fullfanta/mxnet,Prasad9/incubator-mxnet,apaleyes/mxnet,dmlc/mxnet,rishita/mxnet,danithaca/mxnet,danithaca/mxnet,yuruofeifei/mxnet,wangyum/mxnet,larroy/mxnet,likelyzhao/mxnet,EvanzzzZ/mxnet,reminisce/mxnet,sergeykolychev/mxnet,jiajiechen/mxnet,mbaijal/incubator-mxnet,vikingMei/mxnet,weleen/mxnet,thirdwing/mxnet,Guneet-Dhillon/mxnet,reminisce/mxnet,nicklhy/mxnet,gautamkmr/incubator-mxnet,stefanhenneking/mxnet,apache/incubator-mxnet,sergeykolychev/mxnet,CodingCat/mxnet,piiswrong/mxnet,pluskid/mxnet,rahul003/mxnet,rahul003/mxnet,solin319/incubator-mxnet,indhub/mxnet,eric-haibin-lin/mxnet,piiswrong/mxnet,ShownX/incubator-mxnet,tlby/mxnet,kkk669/mxnet,Northrend/mxnet,tlby/mxnet,danithaca/mxnet,leezu/mxnet,yuruofeifei/mxnet,hpi-xnor/BMXNet,apache/incubator-mxnet,crazy-cat/incubator-mxnet,crazy-cat/incubator-mxnet,vikingMei/mxnet,zhreshold/mxnet,yajiedesign/mxnet,TuSimple/mxnet,madjam/mxnet,eric-haibin-lin/mxnet,ptrendx/mxnet,nicklhy/mxnet,crazy-cat/incubator-mxnet,kkk669/mxnet,rahul003/mxnet,jiajiechen/mxnet,formath/mxnet,DR08/mxnet,arank/mxnet,kkk669/mxnet,solin319/incubator-mxnet,ptrendx/mxnet,arank/mxnet,hotpxl/mxnet,zhreshold/mxnet,nicklhy/mxnet,eric-haibin-lin/mxnet,gautamkmr/incubator-mxnet,navrasio/mxnet,eric-haibin-lin/mxnet,danithaca/mxnet,kevinthesun/mxnet,szha/mxnet,leezu/mxnet,crazy-cat/incubator-mxnet,gautamkmr/incubator-mxnet,xcgoner/dist-mxnet,apaleyes/mxnet,CodingCat/mxnet,wangyum/mxnet,luoyetx/mxnet,Mega-DatA-Lab/mxnet,eric-haibin-lin/mxnet,lxn2/mxnet,formath/mxnet,Northrend/mxnet,rishita/mxnet,ForkedReposBak/mxnet,ShownX/incubator-mxnet,leezu/mxnet,rishita/mxnet,ZihengJiang/mxnet,arikpoz/mxnet,precedenceguo/mxnet,antoan2/incubator-mxnet,arank/mxnet,Mega-DatA-Lab/mxnet,antoan2/incubator-mxnet,apaleyes/mxnet,zhreshold/mxnet,leezu/mxnet,larroy/mxnet,ykim362/mxnet,ykim362/mxnet,szha/mxnet,arank/mxnet,mbaijal/incubator-mxnet,dmlc/mxnet,DR08/mxnet,jamesliu/mxnet,ForkedReposBak/mxnet,pluskid/mxnet,sxjscience/mxnet,antoan2/incubator-mxnet,formath/mxnet,LinkHS/incubator-mxnet,luoyetx/mxnet,kevinthesun/mxnet,vikingMei/mxnet,formath/mxnet,madjam/mxnet,ShownX/incubator-mxnet,precedenceguo/mxnet,indhub/mxnet,formath/mxnet,navrasio/mxnet,solin319/incubator-mxnet,luoyetx/mxnet,lxn2/mxnet,eric-haibin-lin/mxnet,ptrendx/mxnet,luoyetx/mxnet,yuruofeifei/mxnet,wangyum/mxnet,antoan2/incubator-mxnet,Ldpe2G/mxnet,larroy/mxnet,indhub/mxnet,navrasio/mxnet,ykim362/mxnet,piiswrong/mxnet,piiswrong/mxnet,rishita/mxnet,indhub/mxnet,ZihengJiang/mxnet,hesseltuinhof/mxnet,nicklhy/mxnet,precedenceguo/mxnet,danithaca/mxnet,zhreshold/mxnet,thirdwing/mxnet,sxjscience/mxnet,madjam/mxnet,lxn2/mxnet,hpi-xnor/BMXNet,CodingCat/mxnet,coder-james/mxnet,ForkedReposBak/mxnet,saurabh3949/mxnet,Mega-DatA-Lab/mxnet,jennyzhang0215/incubator-mxnet,CodingCat/mxnet,EvanzzzZ/mxnet,antoan2/incubator-mxnet,yajiedesign/mxnet,xcgoner/dist-mxnet,yajiedesign/mxnet,likelyzhao/mxnet,kkk669/mxnet,stefanhenneking/mxnet,jamesliu/mxnet,DR08/mxnet,ForkedReposBak/mxnet,gautamkmr/incubator-mxnet,apaleyes/mxnet,xcgoner/dist-mxnet,Ldpe2G/mxnet,szha/mxnet,rishita/mxnet,rahul003/mxnet,hesseltuinhof/mxnet,ShownX/incubator-mxnet,rahul003/mxnet,Mega-DatA-Lab/mxnet,jennyzhang0215/incubator-mxnet,Guneet-Dhillon/mxnet,thirdwing/mxnet,szha/mxnet,sergeykolychev/mxnet,larroy/mxnet,lxn2/mxnet,ShownX/incubator-mxnet,jamesliu/mxnet,tornadomeet/mxnet,sergeykolychev/mxnet,precedenceguo/mxnet,saurabh3949/mxnet,sxjscience/mxnet,indhub/mxnet,eric-haibin-lin/mxnet,saurabh3949/mxnet,EvanzzzZ/mxnet,TuSimple/mxnet,gautamkmr/incubator-mxnet,saurabh3949/mxnet,yajiedesign/mxnet,hpi-xnor/BMXNet,hesseltuinhof/mxnet,Guneet-Dhillon/mxnet,mbaijal/incubator-mxnet,hpi-xnor/BMXNet,lxn2/mxnet,vikingMei/mxnet,coder-james/mxnet,ForkedReposBak/mxnet,navrasio/mxnet,solin319/incubator-mxnet,smolix/incubator-mxnet,jiajiechen/mxnet,weleen/mxnet,precedenceguo/mxnet,szha/mxnet,madjam/mxnet,madjam/mxnet,sergeykolychev/mxnet,pluskid/mxnet,hotpxl/mxnet,kevinthesun/mxnet,luoyetx/mxnet,navrasio/mxnet,EvanzzzZ/mxnet,arikpoz/mxnet,antoan2/incubator-mxnet,jermainewang/mxnet,ptrendx/mxnet,solin319/incubator-mxnet,Guneet-Dhillon/mxnet,stefanhenneking/mxnet,ForkedReposBak/mxnet,crazy-cat/incubator-mxnet,DR08/mxnet,Mega-DatA-Lab/mxnet,DickJC123/mxnet,reminisce/mxnet,CodingCat/mxnet,pluskid/mxnet,indhub/mxnet,precedenceguo/mxnet,Prasad9/incubator-mxnet,mbaijal/incubator-mxnet,leezu/mxnet,apache/incubator-mxnet,Mega-DatA-Lab/mxnet,arank/mxnet,ykim362/mxnet,weleen/mxnet,thirdwing/mxnet