Added utils.flatten(arr) tests
Added utils.flatten(arr) tests

lian774739140/express,gretac/express,WangCao/express,BaggersIO/express,nodejs-camp/booklog-ansaga,v10258/express,hpcslag/express,bercanozcan/express,TestingCI/express,juanpastas/express,YR/express,ericlu88/express,RanadeepPolavarapu/express,FernAbby/express,dongseop/express,chrisinajar/express,za-creature/express,cflynn07/express,devgeniem/express,baldurh/express,rgrove/express,yinhe007/express,PeterWangPo/express,fakedarren/express,awronka/express,hl198181/express,Faiz7412/express,stoskov/express,nbeydoon/express,featurist/express,nodejs-camp/booklog-chle,ahdinosaur/express,ZackBotkin/express,microlv/express,codeforgeek/express,gnowoel/express,benshiue/booklog-ben,ZackBotkin/express,topaxi/express,kunalpict/express,hightechweb/express,weilixia/express,andrejewski/express,brianloveswords/express,svnh/express,auth0/express,Eric-Vandenberg/express,sujianping/express,WebStyle/express,v10258/express,flomotlik/express,tianhengzhou/express,r14r/fork_express_master,stoskov/express,Ivanwangcy/express,dafabulousteach/express,luxe-eng/valet-express.express,BaggersIO/express,gnowoel/express,adjohnson916/express,nodejs-camp/booklog-jollen,samuelcastro/express,listepo/express,supasate/express,1amageek/express,PeterWangPo/express,rupanjanbaidya/express,thepont/express,v10258/express,lemelon/express,sarvex/express,dreamingblackcat/express,buildsample/express,lmtdit/express,nodejs-camp/booklog-tonebeta,dotnetCarpenter/express,TestingCI/express,weilixia/express,devgeniem/express,buildsample/express,sujianping/express,jenalgit/express,fanzetao/express,christopheranderson/express,emvici/emvici-reqres-tify,stevemao/express,kawanet/express,igarciaes/express,nodejs-camp/booklog-mora,Matrixbirds/express,Flip120/express,MoraLin/mora-test,WangCao/express,MoraLin/mora-test,maraoz/express,chuym/express,XueQian/express,kylezhang/express,qitianchan/express,tyler-johnson/express,simudream/express,evilboss/express,chrisinajar/express,strongloop/express,nodejs-camp/booklog-jason,stewartml/express,hdngr/express,wesleytodd/express,KodkodGates/express,corporateanon/express,hacksparrow/express,microlv/express,dotnetCarpenter/express,expressjs/express,youprofit/express,gnowoel/express,elkingtonmcb/express,frootloops/express,abhi3/express,danielrohers/express,evilboss/express,Lexine/express,Haru1990/express,sibura/express,kylezhang/express,FernAbby/express,BaggersIO/express,swstack/express,nathan818fr/express,mcanthony/express,Kevnz/express,kawanet/express,fuse-mars/express,Haru1990/express,danielrohers/express,ci-test2/express,bjrmatos/express,kentcdodds/express,lmtdit/express,hdngr/express,philxia/ex-tst-framework,swarajgiri/express,PUSEN/express,blairzhang/express,auth0/express,featurist/express,abdulhannanali/express,dsupera13/express,angelsanz/express,abdulhannanali/express,simplyianm/express,dafabulousteach/express,nodejs-camp/booklog-mora,igarciaes/express,mikewesthad/express,llwanghong/express,luxe-eng/valet-express.express,simudream/express,junxiong/express,vnglst/express,nodejs-camp/booklog-homa,ralic/express,evanlucas/express,dgofman/express,coreypnorris/express,aifeld/express,wesleytodd/express,hacksparrow/express,llwanghong/express,JulyZhu/express,rgrove/express,soyuka/express,youprofit/express,drzorm/express,topaxi/express,stoskov/express,corporateanon/express,swarajgiri/express,wtony/express,tjmehta/express,nodejs-camp/booklog-archer,aifeld/express,hanqingnan/express,philxia/ex-tst-framework,robomc/express,blakeembrey/express,nodejs-camp/booklog-polo,dafabulousteach/express,frootloops/express,jinghuizhai/express,michaeljunlove/express,youprofit/express,qq645381995/express,lmtdit/express,jenia0jenia/express,demohi/express,nodejs-camp/booklog-s890506,nathan818fr/express,Jonekee/express,WebStyle/express,jenia0jenia/express,Faiz7412/express,jinghuizhai/express,udhayam/express,strongloop/express,nodejs-camp/booklog-ansaga,pshomov/express,stevemao/express,Ju2ender/express,lian774739140/express,mikewesthad/express,nodejs-camp/booklog-archer,abhi3/express,YR/express,xiaofuzi/express,saisai/express,nodejs-camp/booklog-jason,nodejs-camp/booklog-s890506,baldurh/express,abdulhannanali/express,xiaofuzi/express,KodkodGates/express,nodejs-camp/booklog-leo,vnglst/express,philxia/ex-tst-framework,juanpastas/express,benshiue/booklog-ben,nodejs-camp/booklog-chenyou,juandav/express,pstrike/express,za-creature/express,KodkodGates/express,wtony/express,nodejs-camp/booklog-ausir,grigorkh/express,luxe-eng/valet-express.express,VegeChou/express,supasate/express,jenalgit/express,buildsample/express,chuym/express,sarvex/express,leiqiang75/express,saisai/express,caiocutrim/express,blainsmith/express,kentcdodds/express,Eric-Vandenberg/express,nodejs-camp/booklog-homa,dongseop/express,coreypnorris/express,CrazySherman/express,dongooo/express,isaacs/express,dieuly/express,leiqiang75/express,btleffler/express,philxia/ex-tst-framework,pstrike/express,jymsy/express,codeforgeek/express,neomadara/express,stewartml/express,xiaofuzi/express,kubrickology/express,fakedarren/express,jimmykuo/express,caiocutrim/express,LestaD/express,qitianchan/express,andriyl/express,hanweifish/express,mauricionr/express,michaeljunlove/express,methuz/express,demohi/express,PUSEN/express,blairzhang/express,1amageek/express,hpcslag/express,blairzhang/express,friederbluemle/express,listepo/express,Eric-Vandenberg/express,devgeniem/express,Talkyunyun/express,jymsy/express,rupanjanbaidya/express,fineday32/express,r14r/fork_express_master,nodejs-camp/booklog-leo,VegeChou/express,dotnetCarpenter/express,nodejs-camp/booklog-tonebeta-update,nodejs-camp/booklog-ben,supasate/express,hanweifish/express,Ju2ender/express,ahdinosaur/express,Riokai/express,jinghuizhai/express,1verson/express,corporateanon/express,fineday32/express,andriyl/express,friederbluemle/express,michaeljunlove/express,friederbluemle/express,nodejs-camp/booklog-polo,Kevnz/express,chrisinajar/express,andrejewski/express,cflynn07/express,isaacs/express,qitianchan/express,1amageek/express,tyler-johnson/express,tianhengzhou/express,HXYNODE/express,LestaD/express,ifraixedes/express,JulyZhu/express,Riokai/express,udhayam/express,ericlu88/express,svnh/express,jenia0jenia/express,juandav/express,za-creature/express,smcmurray/express,Jonekee/express,neomadara/express,junxiong/express,maraoz/express,dongooo/express,mcanthony/express,gdeividas/express,dieuly/express,elkingtonmcb/express,pathirana/express,nodejs-camp/booklog-chle,vinodhalaharvi/express,vidyar/express,fakedarren/express,nodejs-camp/booklog-tonebeta,srichatala/express,RanadeepPolavarapu/express,evanlucas/express,ralic/express,vnglst/express,HXYNODE/express,nbeydoon/express,topaxi/express,RickyDan/express,ci-test2/express,srichatala/express,yinhe007/express,kunalpict/express,dreamingblackcat/express,blakeembrey/express,RickyDan/express,gdeividas/express,featurist/express,samuelcastro/express,Ivanwangcy/express,TestingCI/express,XueQian/express,shanawarkhan/express,pathirana/express,smcmurray/express,CrazySherman/express,heicx/express,Flip120/express,mimaidms/express,WangCao/express,nodejs-camp/booklog-ben,hdngr/express,robomc/express,bjrmatos/express,soyuka/express,expressjs/express,bercanozcan/express,Talkyunyun/express,sarvex/express,nodejs-camp/booklog-jollen,swstack/express,mimaidms/express,Matrixbirds/express,tjmehta/express,qq645381995/express,btleffler/express,1verson/express,vinodhalaharvi/express,nodejs-camp/booklog-linkchen,kunalpict/express,maraoz/express,thepont/express,vidyar/express,mauricionr/express,xtidt/express,nodejs-camp/booklog-tonebeta-update,hpcslag/express,nodejs-camp/booklog-linkchen,simplyianm/express,kubrickology/express,sibura/express,bercanozcan/express,jenalgit/express,nbeydoon/express,jimmykuo/express,LestaD/express,ci-test2/express,christopheranderson/express,blakeembrey/express,stevemao/express,abhi3/express,hl198181/express,r14r-work/fork_express_master,stewartml/express,evilboss/express,fanzetao/express,adjohnson916/express,nodejs-camp/booklog-chenyou,lemelon/express,micha149/express,countdracular/express,gretac/express,coreypnorris/express,Riokai/express,ifraixedes/express,swarajgiri/express,kylezhang/express,listepo/express,vidyar/express,Lexine/express,heicx/express,blainsmith/express,dgofman/express,hanqingnan/express,methuz/express,Flip120/express,Ju2ender/express,Faiz7412/express,wtony/express,svnh/express,simudream/express,smcmurray/express,XueQian/express,xtidt/express,shanawarkhan/express,nodejs-camp/booklog-Zak,qq645381995/express,grigorkh/express,angelsanz/express,dreamingblackcat/express,ZackBotkin/express,micha149/express,drzorm/express,countdracular/express,fuse-mars/express,nodejs-camp/booklog-polo,nodejs-camp/booklog-ausir,dsupera13/express,dongseop/express,junxiong/express,hightechweb/express,vinodhalaharvi/express,angelsanz/express,grigorkh/express,flomotlik/express,pshomov/express,nodejs-camp/booklog-Zak,r14r-work/fork_express_master,awronka/express