MAINT: Break up FFT convolve for readability, etc.
MAINT: Break up FFT convolve for readability, etc.

FFT convolution was a single command split across three lines, now it's
3 commands.

Also:

Move imports to top of file

Combine equality checks a == 1 and b == 1 -> a == b == 1
(shorter, more readable, slightly faster)

Replace len(var.shape) with var.ndim

Clarify that slice object reverses along all axes

sriki18/scipy,woodscn/scipy,person142/scipy,jamestwebber/scipy,vigna/scipy,kleskjr/scipy,kleskjr/scipy,jamestwebber/scipy,bkendzior/scipy,Gillu13/scipy,pyramania/scipy,tylerjereddy/scipy,endolith/scipy,lhilt/scipy,woodscn/scipy,anntzer/scipy,Eric89GXL/scipy,Newman101/scipy,ilayn/scipy,anielsen001/scipy,Stefan-Endres/scipy,gfyoung/scipy,nmayorov/scipy,josephcslater/scipy,tylerjereddy/scipy,perimosocordiae/scipy,nmayorov/scipy,ilayn/scipy,surhudm/scipy,nmayorov/scipy,befelix/scipy,jamestwebber/scipy,matthewalbani/scipy,surhudm/scipy,anielsen001/scipy,pyramania/scipy,gertingold/scipy,ilayn/scipy,anielsen001/scipy,dominicelse/scipy,e-q/scipy,pbrod/scipy,zerothi/scipy,maniteja123/scipy,woodscn/scipy,nonhermitian/scipy,gertingold/scipy,scipy/scipy,haudren/scipy,anntzer/scipy,Stefan-Endres/scipy,gdooper/scipy,dominicelse/scipy,vigna/scipy,behzadnouri/scipy,niknow/scipy,andyfaff/scipy,rgommers/scipy,vigna/scipy,kalvdans/scipy,WarrenWeckesser/scipy,josephcslater/scipy,aarchiba/scipy,bkendzior/scipy,rgommers/scipy,scipy/scipy,jor-/scipy,jakevdp/scipy,haudren/scipy,aeklant/scipy,jakevdp/scipy,matthewalbani/scipy,Gillu13/scipy,jakevdp/scipy,e-q/scipy,Newman101/scipy,jjhelmus/scipy,pbrod/scipy,Newman101/scipy,anntzer/scipy,lhilt/scipy,gdooper/scipy,sriki18/scipy,behzadnouri/scipy,matthew-brett/scipy,pyramania/scipy,lhilt/scipy,pschella/scipy,Stefan-Endres/scipy,aarchiba/scipy,perimosocordiae/scipy,Eric89GXL/scipy,Newman101/scipy,woodscn/scipy,rgommers/scipy,andyfaff/scipy,Gillu13/scipy,apbard/scipy,surhudm/scipy,ilayn/scipy,aarchiba/scipy,ilayn/scipy,mikebenfield/scipy,maniteja123/scipy,Stefan-Endres/scipy,matthewalbani/scipy,kleskjr/scipy,andyfaff/scipy,andyfaff/scipy,gdooper/scipy,Eric89GXL/scipy,pschella/scipy,anntzer/scipy,pschella/scipy,dominicelse/scipy,zerothi/scipy,gfyoung/scipy,ilayn/scipy,kleskjr/scipy,argriffing/scipy,pyramania/scipy,niknow/scipy,person142/scipy,vigna/scipy,gdooper/scipy,Eric89GXL/scipy,arokem/scipy,perimosocordiae/scipy,josephcslater/scipy,argriffing/scipy,behzadnouri/scipy,apbard/scipy,maniteja123/scipy,jor-/scipy,pbrod/scipy,jor-/scipy,mikebenfield/scipy,grlee77/scipy,jamestwebber/scipy,pbrod/scipy,befelix/scipy,zerothi/scipy,matthew-brett/scipy,perimosocordiae/scipy,nmayorov/scipy,Eric89GXL/scipy,haudren/scipy,sriki18/scipy,maniteja123/scipy,gertingold/scipy,endolith/scipy,anielsen001/scipy,behzadnouri/scipy,niknow/scipy,mdhaber/scipy,mikebenfield/scipy,dominicelse/scipy,kalvdans/scipy,scipy/scipy,jor-/scipy,nonhermitian/scipy,niknow/scipy,anielsen001/scipy,pizzathief/scipy,gertingold/scipy,scipy/scipy,WarrenWeckesser/scipy,endolith/scipy,jakevdp/scipy,befelix/scipy,andyfaff/scipy,grlee77/scipy,grlee77/scipy,e-q/scipy,arokem/scipy,apbard/scipy,kleskjr/scipy,jjhelmus/scipy,e-q/scipy,lhilt/scipy,WarrenWeckesser/scipy,bkendzior/scipy,perimosocordiae/scipy,pyramania/scipy,zerothi/scipy,andyfaff/scipy,jjhelmus/scipy,gertingold/scipy,josephcslater/scipy,jor-/scipy,bkendzior/scipy,kalvdans/scipy,arokem/scipy,haudren/scipy,behzadnouri/scipy,anielsen001/scipy,grlee77/scipy,kalvdans/scipy,matthew-brett/scipy,aeklant/scipy,nonhermitian/scipy,tylerjereddy/scipy,jjhelmus/scipy,anntzer/scipy,Stefan-Endres/scipy,matthewalbani/scipy,argriffing/scipy,perimosocordiae/scipy,endolith/scipy,befelix/scipy,aarchiba/scipy,gdooper/scipy,mdhaber/scipy,surhudm/scipy,nonhermitian/scipy,nonhermitian/scipy,rgommers/scipy,gfyoung/scipy,pbrod/scipy,sriki18/scipy,person142/scipy,kalvdans/scipy,matthew-brett/scipy,mdhaber/scipy,Gillu13/scipy,lhilt/scipy,pbrod/scipy,Gillu13/scipy,josephcslater/scipy,aarchiba/scipy,maniteja123/scipy,kleskjr/scipy,endolith/scipy,befelix/scipy,apbard/scipy,zerothi/scipy,gfyoung/scipy,anntzer/scipy,pizzathief/scipy,mdhaber/scipy,pschella/scipy,WarrenWeckesser/scipy,mdhaber/scipy,maniteja123/scipy,woodscn/scipy,tylerjereddy/scipy,rgommers/scipy,endolith/scipy,behzadnouri/scipy,Stefan-Endres/scipy,jakevdp/scipy,Gillu13/scipy,bkendzior/scipy,apbard/scipy,e-q/scipy,argriffing/scipy,dominicelse/scipy,Newman101/scipy,pizzathief/scipy,scipy/scipy,matthewalbani/scipy,arokem/scipy,argriffing/scipy,WarrenWeckesser/scipy,sriki18/scipy,mdhaber/scipy,scipy/scipy,arokem/scipy,tylerjereddy/scipy,sriki18/scipy,mikebenfield/scipy,person142/scipy,aeklant/scipy,aeklant/scipy,WarrenWeckesser/scipy,gfyoung/scipy,vigna/scipy,matthew-brett/scipy,haudren/scipy,argriffing/scipy,Newman101/scipy,zerothi/scipy,pizzathief/scipy,niknow/scipy,pizzathief/scipy,pschella/scipy,niknow/scipy,woodscn/scipy,aeklant/scipy,grlee77/scipy,jjhelmus/scipy,nmayorov/scipy,surhudm/scipy,haudren/scipy,jamestwebber/scipy,person142/scipy,Eric89GXL/scipy,mikebenfield/scipy,surhudm/scipy