Re-add some functions and a docstring from master.
Re-add some functions and a docstring from master.

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