Docstring to ._series() added.
Docstring to ._series() added.

Signed-off-by: Kirill Smelkov <b0eeaac46e675e9f95bf68c0df1041cf581c26f4@landau.phys.spbu.ru>

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