minor fix to exception name
minor fix to exception name

Its "NotImplementedError" rather than "NotImplemented".

MechCoder/sympy,toolforger/sympy,Gadal/sympy,wanglongqi/sympy,Davidjohnwilson/sympy,hargup/sympy,yashsharan/sympy,skidzo/sympy,lindsayad/sympy,abhiii5459/sympy,pandeyadarsh/sympy,Titan-C/sympy,Gadal/sympy,yashsharan/sympy,AkademieOlympia/sympy,VaibhavAgarwalVA/sympy,bukzor/sympy,toolforger/sympy,aktech/sympy,farhaanbukhsh/sympy,kaushik94/sympy,ChristinaZografou/sympy,moble/sympy,ChristinaZografou/sympy,iamutkarshtiwari/sympy,yukoba/sympy,Gadal/sympy,ga7g08/sympy,kaushik94/sympy,chaffra/sympy,ga7g08/sympy,souravsingh/sympy,cswiercz/sympy,Curious72/sympy,garvitr/sympy,hargup/sympy,atsao72/sympy,sahilshekhawat/sympy,jerli/sympy,maniteja123/sympy,emon10005/sympy,hargup/sympy,grevutiu-gabriel/sympy,drufat/sympy,asm666/sympy,Arafatk/sympy,cswiercz/sympy,postvakje/sympy,atreyv/sympy,abloomston/sympy,Mitchkoens/sympy,Curious72/sympy,jaimahajan1997/sympy,farhaanbukhsh/sympy,yukoba/sympy,skidzo/sympy,Titan-C/sympy,ga7g08/sympy,Shaswat27/sympy,bukzor/sympy,asm666/sympy,kaichogami/sympy,mafiya69/sympy,sahmed95/sympy,saurabhjn76/sympy,kumarkrishna/sympy,grevutiu-gabriel/sympy,shikil/sympy,sampadsaha5/sympy,kaushik94/sympy,yukoba/sympy,kaichogami/sympy,Vishluck/sympy,pbrady/sympy,sampadsaha5/sympy,pbrady/sympy,Shaswat27/sympy,mcdaniel67/sympy,shikil/sympy,lindsayad/sympy,atreyv/sympy,cswiercz/sympy,MechCoder/sympy,wanglongqi/sympy,VaibhavAgarwalVA/sympy,iamutkarshtiwari/sympy,atsao72/sympy,sahilshekhawat/sympy,wyom/sympy,Davidjohnwilson/sympy,wyom/sympy,atsao72/sympy,jbbskinny/sympy,yashsharan/sympy,jbbskinny/sympy,rahuldan/sympy,aktech/sympy,mcdaniel67/sympy,pbrady/sympy,pandeyadarsh/sympy,oliverlee/sympy,drufat/sympy,emon10005/sympy,toolforger/sympy,kevalds51/sympy,debugger22/sympy,souravsingh/sympy,kumarkrishna/sympy,abloomston/sympy,aktech/sympy,postvakje/sympy,drufat/sympy,ChristinaZografou/sympy,madan96/sympy,jerli/sympy,ahhda/sympy,saurabhjn76/sympy,maniteja123/sympy,Titan-C/sympy,jbbskinny/sympy,saurabhjn76/sympy,Designist/sympy,kevalds51/sympy,maniteja123/sympy,debugger22/sympy,sahmed95/sympy,AkademieOlympia/sympy,Davidjohnwilson/sympy,grevutiu-gabriel/sympy,Mitchkoens/sympy,skidzo/sympy,chaffra/sympy,Arafatk/sympy,Designist/sympy,kevalds51/sympy,garvitr/sympy,VaibhavAgarwalVA/sympy,mafiya69/sympy,rahuldan/sympy,moble/sympy,debugger22/sympy,souravsingh/sympy,Designist/sympy,atreyv/sympy,jaimahajan1997/sympy,jerli/sympy,emon10005/sympy,kaichogami/sympy,jaimahajan1997/sympy,sahmed95/sympy,oliverlee/sympy,lindsayad/sympy,abhiii5459/sympy,Vishluck/sympy,mafiya69/sympy,asm666/sympy,Shaswat27/sympy,wyom/sympy,abhiii5459/sympy,MechCoder/sympy,rahuldan/sympy,Arafatk/sympy,mcdaniel67/sympy,madan96/sympy,kumarkrishna/sympy,garvitr/sympy,chaffra/sympy,Vishluck/sympy,abloomston/sympy,moble/sympy,farhaanbukhsh/sympy,shikil/sympy,pandeyadarsh/sympy,Mitchkoens/sympy,sahilshekhawat/sympy,wanglongqi/sympy,ahhda/sympy,postvakje/sympy,oliverlee/sympy,Curious72/sympy,ahhda/sympy,iamutkarshtiwari/sympy,AkademieOlympia/sympy,bukzor/sympy,madan96/sympy,sampadsaha5/sympy