anchor.diff:    `(or (eql :always)
          (eql :ignore)
          (eql :confirm)))
  +
  +(deftype function-symbol ()
  +  `(and symbol (satisfies fboundp)))
   
   (defun exported-p (sym)
     (eq :external
  
positive.code: 
                        (setf (slot-value source 'suggestions) '())
                        (if (or (str:empty? input)
                                (not (functionp (filter source))))
                            (setf (slot-value source 'suggestions) preprocessed-suggestions)
                            (dolist (suggestion preprocessed-suggestions)
                              (sera:and-let* ((processed-suggestion
  
negative.code: - (optional) current input.")
  
       (filter #'fuzzy-match
               :type (or null function function-symbol)
               :documentation
               "Takes `input' and a `suggestion' and return a new suggestion, or
  nil if the suggestion is discarded.")
  