anchor.diff:  ;;;
   ;;; Instruction SLOT-READ-INSTRUCTION.
   ;;;
  -;;; This instruction takes a two inputs.  The first input is assumed
  +;;; This instruction takes two inputs.  The first input is assumed
   ;;; to be a standard instance.  The second is assumed to be a FIXNUM
   ;;; and represents the index in the instance of the slot to be read.
   ;;; This instruction produces a single output, which is the contents
  
positive.code:     :inputs (list input1 input2 input3)
      :outputs ()
      :successors (list successor)))
  
  
negative.code: ;;;
  ;;; Instruction SINGLE-FLOAT-AREF-INSTRUCTION.
  ;;;
  ;;; This instruction takes two inputs.  The first input is assumed
  ;;; to be an array specialized to SINGLE-FLOAT.  The second is assumed
  ;;; to be a FIXNUM and represents the index in the instance of the
  ;;; element to be read.  This instruction produces a single output,
  