anchor.diff:  									   :defaults error)
   									  directory))))))
   
  -(defun prepare-slurm-script (directory area tree program &key (if-exists :error if-exists-p) (output "stdout/") (error :output))
  +(defun prepare-slurm-script (directory area tree program &key (if-exists :error if-exists-p) (output "stdout/") (error :output) (group-size 1))
     (declare (type (member :error :supersede :supersede-all) if-exists))
     (let ((program-path (if (listp program)
   			  (apply #'lisp-executable-pathname program)
  
positive.code: 
  	  (with-open-file (out "slurm-program.sh" :if-exists if-exists :direction :output)
  	    (format out "#!/bin/sh~%")
  	    (format out "~S `cat ~S` $1 $2 $(( ${SLURM_ARRAY_TASK_ID} - 1 ))~%"
  		    (namestring program-path)
  		    (namestring (merge-pathnames "slurm-program-arguments"))))
  
  	  (with-open-file (out "slurm.sh" :if-exists if-exists :direction :output)
  
negative.code: echo ${LEVEL~d}
  "
  			 depth
  			 (floor count group-size)
  			 (determine-slurm-output-arguments directory output error)
  			 (pathname-name program-path)
  			 (namestring (merge-pathnames "slurm-arguments"))
  