```common lisp
(cl:in-package #:clump-binary-tree)

(defmethod acclimation:report-condition
    ((condition invalid-binary-tree)
     stream
     (language acclimation:english))
  (format stream
	  "A binary tree was expected,~@
           but instead the following was found:~@
           ~s"
	  (tree condition)))
```

Add English condition reporter for RIGHT-SUBTREE-MUST-BE-NON-NIL.
user
```common lisp
(cl:in-package #:clump-binary-tree)

(defmethod acclimation:report-condition
    ((condition invalid-binary-tree)
     stream
     (language acclimation:english))
  (format stream
	  "A binary tree was expected,~@
           but instead the following was found:~@
           ~s"
	  (tree condition)))

(defmethod acclimation:report-condition
    ((condition right-subtree-must-be-non-nil)
     stream
     (language acclimation:english))
  (format stream
	  "The right subtree of the following tree,~@
           is NIL, but a non-NIL subtree is required:~@
           ~s"
	  (tree condition)))
```
assistant