can someone help me figure this out

[eleonard]

My pregnant brain just doesn't want to understand lisp these days.
I have a new employee using this and i can't figure out what this routine is actually doing.

(defun item (n e)
    (cdr (assoc n e))
  )
  (defun mend-error (s)
    (if (\= s "Function cancelled")
  	(princ s)
    )
    (if ename1
  	(redraw ename1 4)
    )
    (command ".UNDO" "END")
    (setvar "CMDECHO" 1)
    (princ)
  )
  (defun selent (typ ord /)
    (setq en nil)
    (if (= ord 0)
  	(setq ord "")
    )
    (if (= ord 1)
  	(setq ord "first ")
    )
    (if (= ord 2)
  	(setq ord "second ")
    )
    (while (null en)
  	(if	(setq en (entsel (strcat "\nSelect " ord typ ": ")))
  	  (progn
  	(setq ename (car en))
  	(setq edata (entget ename))
  	(if (/= (cdr (assoc 0 edata)) (strcase typ))
  	  (progn
  		(prompt "\nEntity is a ")
  		(princ (cdr (assoc 0 edata)))
  		(setq en nil)
  	  )
  	  (redraw ename 3)
  	)
  	  )
  	)
    )
  )
  (defun mend1 (/	ans ok es1 ename1 int1 int2 ent1 es2 ename2 ent2 plist
  		  qlist)
    (setq ans nil)
    (if (not selent)
  	(load "selent")
    )
    (selent "LINE" 1)
    (setq	ent1   edata
  	ename1 ename
    )
    (selent "LINE" 2)
    (setq	ent2   edata
  	ename2 ename
    )
    (setq	int1 (inters (cdr (assoc 10 ent1))
  			 (cdr (assoc 10 ent2))
  			 (cdr (assoc 10 ent1))
  			 (cdr (assoc 11 ent2))
  			 nil
  		 )
    )
    (setq	int2 (inters (cdr (assoc 11 ent1))
  			 (cdr (assoc 10 ent2))
  			 (cdr (assoc 11 ent1))
  			 (cdr (assoc 11 ent2))
  			 nil
  		 )
    )
    (if (or int1 int2)
  	(progn
  	  (initget "Yes No")
  	  (setq
  	ans (getkword
  		  "\nSegments are not on same line - join anyway? <N>: "
  		)
  	  )
  	  (if (= ans nil)
  	(setq ans "No")
  	  )
  	)
    )
    (if (/= ans "No")
  	(progn
  	  (setq plist (mapcar '(lambda (p1 p2)
  				 (list (distance (item p1 ent1)
 		 			 (item p2 ent2)
  				   )
  				   p1
  				   p2
  				 )
  			   )
  			  '(10 10 11 11)
  			  '(10 11 10 11)
  		  )
  		qlist (item (apply 'max (mapcar 'car plist)) plist)
  		ent1  (subst (cons (- 21 (car qlist)) (item (cadr qlist) ent2))
  			 (assoc (- 21 (car qlist)) ent1)
  			 ent1
  		  )
  	  )
  	  (entdel ename2)
  	  (entmod ent1)
  	)
  	(progn
  	  (if ename1
  	(redraw ename1 4)
  	  )
  	  (if ename2
  	(redraw ename2 4)
  	  )
  	)
    )
  )
  (defun c:mend (/ olderror *error* ce)
    (prompt "\nCommand: MEND ")
    (setq	ce	 (getvar "CMDECHO")
  	olderror *error*
  	*error*	 mend-error
    )
    (setvar "CMDECHO" 0)
    (command ".UNDO" "begin")
    (mend1)
    (command "UNDO" "END")
    (setvar "CMDECHO" 1)
    (print)
    (print)
  )

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[Jeff_M]

It appears to be a function that "mends" 2 lines into 1, first checking that both lines are parallel.

Jeff