subroutine char MY_KEY
! show vari MY_KEY
! echo " -------------- NEW LINE ------------"
! wr sele MY_KEY end coor pdb
set vari IATOM inte atom sele MY_KEY end
! show vari IATOM 
if ( IATOM .le. 0 ) return
set vari IATOM2 inte atom sele by bond atom numb IATOM end
! show vari IATOM2
! wr sele atom numb IATOM IATOM2 end coor pdb

! echo JOIN RESIDUE IATOM IATOM2

join resi IATOM2 IATOM
!rena seq Z sele by resi atom numb IATOM end append
!rena resi CTR sele by resi atom numb IATOM end 
! wr sele by resi atom numb IATOM end coor pdb

key MY_KEY sele MY_KEY .a .n atom numb IATOM end
rewind file
return