+(defun lambda-ancestor-p (maybe-ancestor maybe-descendant)
+ (declare (type clambda maybe-ancestor)
+ (type (or clambda null) maybe-descendant))
+ (loop
+ (when (eq maybe-ancestor maybe-descendant)
+ (return t))
+ (setf maybe-descendant (lambda-parent maybe-descendant))
+ (when (null maybe-descendant)
+ (return nil))))
+