anchor.diff:                           (clavier:is-an-integer))
             :default default
             :required-p required-p
  -          :if-invalid (or (parse-if-invalid if-invalid)
  +          :if-invalid (or (parse-if-invalid if-invalid error-color)
                             (lambda (&rest args)
                               (declare (ignore args))
                               (say "Error: Not a number" :color error-color)))
  
positive.code:                          (return nil))
                          ((not parsed-input)
                           (if if-invalid
                               (funcall (parse-if-invalid if-invalid))
                               (say "Invalid value" :color error-color)))
                          (parsed-input
                           (return parsed-input)))))))
  
negative.code:               :validator (or (and validator (clavier:&& (clavier:valid-email)
                                                          (make-validator validator)))
                               (clavier:valid-email))
                :if-invalid (or (parse-if-invalid if-invalid error-color)
                                (lambda (&optional value)
                                  (declare (ignore value))
                                  (say "Invalid email" :color error-color)))
  