func get_frame(cube, it, nx, ny)
 ;nx and ny are returned values, the size of frame it in cube
 ;also returns the image as function value
 if issymarr(cube) then {
   image = cube(it)
   ;;nx = dimen_symarr(cube, it, 0)
   ;;ny = dimen_symarr(cube, it, 1)
 } else {
   image = cube(*,*,it)
   ;;nx = dimen(cube,0)
   ;;ny = dimen(cube,1)
 }
 nx = dimen(image,0)
 ny = dimen(image,1)
 return, image
 endfunc
 ;========================================================