perm_groups: expand is_group docstring and modify generate docstring
perm_groups: expand is_group docstring and modify generate docstring

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