doctest for simplify() added
doctest for simplify() added

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