anchor.diff:  (defparameter *use-debugger* nil
     "If not NIL, enter the debugger when an error is encountered in an
   assertion.")
  +
  +(defparameter *signal-results* nil
  +  "Signal the result if non NIL.")
   
   (defun use-debugger-p (condition)
     "Debug or ignore errors."
  
positive.code:    (push test-name (missing-tests results))
     ;; Summarize and return the test results
     finally
     (summarize-results results)
      (signal 'test-run-complete :results results)
     (return results)))
  
  (defun %run-thunks (test-names &optional (package *package*))
  
negative.code:            :print-errors
             :summarize-results)
    ;; Functions for extensibility via signals
    (:export :signal-results
             :test-run-complete
             :results)
    ;; Utility predicates
    (:export :logically-equal :set-equal))
  