core: Remove unused import from singleton
core: Remove unused import from singleton

yukoba/sympy,sahmed95/sympy,yukoba/sympy,yashsharan/sympy,AkademieOlympia/sympy,pandeyadarsh/sympy,hargup/sympy,abhiii5459/sympy,atreyv/sympy,kaushik94/sympy,ga7g08/sympy,liangjiaxing/sympy,beni55/sympy,jaimahajan1997/sympy,sunny94/temp,chaffra/sympy,Mitchkoens/sympy,AunShiLord/sympy,jerli/sympy,ga7g08/sympy,liangjiaxing/sympy,garvitr/sympy,Shaswat27/sympy,emon10005/sympy,madan96/sympy,oliverlee/sympy,minrk/sympy,postvakje/sympy,jaimahajan1997/sympy,atreyv/sympy,Vishluck/sympy,Gadal/sympy,yashsharan/sympy,yashsharan/sympy,cccfran/sympy,Arafatk/sympy,emon10005/sympy,moble/sympy,saurabhjn76/sympy,debugger22/sympy,Davidjohnwilson/sympy,ahhda/sympy,Shaswat27/sympy,skirpichev/omg,meghana1995/sympy,jbbskinny/sympy,wanglongqi/sympy,grevutiu-gabriel/sympy,maniteja123/sympy,MechCoder/sympy,abloomston/sympy,oliverlee/sympy,VaibhavAgarwalVA/sympy,diofant/diofant,sahilshekhawat/sympy,pbrady/sympy,chaffra/sympy,garvitr/sympy,Davidjohnwilson/sympy,saurabhjn76/sympy,cccfran/sympy,mcdaniel67/sympy,aktech/sympy,shikil/sympy,pandeyadarsh/sympy,MridulS/sympy,amitjamadagni/sympy,shipci/sympy,abhiii5459/sympy,farhaanbukhsh/sympy,aktech/sympy,ChristinaZografou/sympy,rahuldan/sympy,pandeyadarsh/sympy,chaffra/sympy,garvitr/sympy,hrashk/sympy,shikil/sympy,liangjiaxing/sympy,Sumith1896/sympy,sunny94/temp,drufat/sympy,kumarkrishna/sympy,sahmed95/sympy,farhaanbukhsh/sympy,mafiya69/sympy,shikil/sympy,moble/sympy,toolforger/sympy,Arafatk/sympy,srjoglekar246/sympy,jbbskinny/sympy,atsao72/sympy,lidavidm/sympy,vipulroxx/sympy,lidavidm/sympy,jerli/sympy,lindsayad/sympy,ga7g08/sympy,sahmed95/sympy,souravsingh/sympy,sahilshekhawat/sympy,wanglongqi/sympy,iamutkarshtiwari/sympy,Mitchkoens/sympy,moble/sympy,Sumith1896/sympy,pbrady/sympy,hargup/sympy,Gadal/sympy,vipulroxx/sympy,yukoba/sympy,VaibhavAgarwalVA/sympy,lindsayad/sympy,toolforger/sympy,beni55/sympy,ChristinaZografou/sympy,mafiya69/sympy,wanglongqi/sympy,cccfran/sympy,atreyv/sympy,jbbskinny/sympy,AkademieOlympia/sympy,MechCoder/sympy,sunny94/temp,MridulS/sympy,rahuldan/sympy,Designist/sympy,wyom/sympy,abloomston/sympy,sahilshekhawat/sympy,souravsingh/sympy,jamesblunt/sympy,flacjacket/sympy,Mitchkoens/sympy,Curious72/sympy,abhiii5459/sympy,MechCoder/sympy,sampadsaha5/sympy,dqnykamp/sympy,drufat/sympy,Curious72/sympy,Arafatk/sympy,kevalds51/sympy,VaibhavAgarwalVA/sympy,asm666/sympy,bukzor/sympy,meghana1995/sympy,postvakje/sympy,oliverlee/sympy,Shaswat27/sympy,minrk/sympy,beni55/sympy,aktech/sympy,grevutiu-gabriel/sympy,grevutiu-gabriel/sympy,kmacinnis/sympy,kmacinnis/sympy,kaushik94/sympy,MridulS/sympy,madan96/sympy,kaushik94/sympy,Designist/sympy,shipci/sympy,Titan-C/sympy,sampadsaha5/sympy,ahhda/sympy,debugger22/sympy,hargup/sympy,kevalds51/sympy,Curious72/sympy,skidzo/sympy,Vishluck/sympy,cswiercz/sympy,Gadal/sympy,AunShiLord/sympy,Davidjohnwilson/sympy,atsao72/sympy,hrashk/sympy,ChristinaZografou/sympy,hrashk/sympy,iamutkarshtiwari/sympy,jerli/sympy,cswiercz/sympy,lidavidm/sympy,Sumith1896/sympy,mcdaniel67/sympy,maniteja123/sympy,jaimahajan1997/sympy,cswiercz/sympy,Vishluck/sympy,bukzor/sympy,asm666/sympy,skidzo/sympy,jamesblunt/sympy,debugger22/sympy,AkademieOlympia/sympy,toolforger/sympy,kaichogami/sympy,ahhda/sympy,souravsingh/sympy,atsao72/sympy,AunShiLord/sympy,bukzor/sympy,kmacinnis/sympy,emon10005/sympy,kaichogami/sympy,jamesblunt/sympy,iamutkarshtiwari/sympy,drufat/sympy,wyom/sympy,pbrady/sympy,farhaanbukhsh/sympy,asm666/sympy,mafiya69/sympy,skidzo/sympy,kumarkrishna/sympy,saurabhjn76/sympy,dqnykamp/sympy,vipulroxx/sympy,rahuldan/sympy,Designist/sympy,postvakje/sympy,dqnykamp/sympy,abloomston/sympy,meghana1995/sympy,amitjamadagni/sympy,wyom/sympy,mcdaniel67/sympy,shipci/sympy,kumarkrishna/sympy,kevalds51/sympy,kaichogami/sympy,Titan-C/sympy,lindsayad/sympy,Titan-C/sympy,madan96/sympy,sampadsaha5/sympy,maniteja123/sympy