since flask-wtf has not merged my pr, let's make it a built-in
since flask-wtf has not merged my pr, let's make it a built-in

pythoncn/june,jubel-han/june,beni55/june,xingkaixin/june,yuewolf/june,Ricardo666666/june,yuewolf/june,w15971597/june,Ricardo666666/june,yuewolf/june,Denniskevin/june,w15971597/june,fanne/june,fanne/june,beni55/june,jubel-han/june,Denniskevin/june,Ricardo666666/june,fanne/june,w15971597/june,Denniskevin/june,xingkaixin/june,jubel-han/june,pythoncn/june,xingkaixin/june,beni55/june