(defun cvs-tree-merge (tree1 tree2)
"Merge tags trees TREE1 and TREE2 into one.
-BEWARE: because of stability issues, this is not a symetric operation."
+BEWARE: because of stability issues, this is not a symmetric operation."
(assert (and (listp tree1) (listp tree2)))
(cond
((null tree1) tree2)