anchor.diff:  ;; These elements should have been removed by LOOP-TO-FUNCTION
   (forbid-transformation-elements explicitize (do-statement for))
   
  -;;================================================================================
  -;;;; TX-EXPLICITIZE methods
  +;;;; ======= TX-EXPLICITIZE methods ================================================================
   
   (defgeneric tx-explicitize (elm)
     (:documentation
  
positive.code:   `(let ((*nested-context* t))
      ,@body))
  
  ;;================================================================================
  ;;;; TRANSFORM method
  
  (defmethod transform ((xform (eql 'explicitize)) elm)
    (multiple-value-bind (proxy prereqs)
  
negative.code: ;;; The second value is a list of "prerequisite" statements that should go before the
  ;;; innermost enclosing non-nested statement (which may be this statement).
  
  ;;;; ======= Sub-expression protocol ===============================================================
  ;;;
  ;;; Transformations are responsible for knowing whether they are nested within subexpressions
  ;;; or not, and therefore whether they should return using a proxy.  For example, the element
  