* README.md: code correction

README.md

@@ -349,21 +349,22 @@ If you look in <code>src/logic_tutorial/tut3.clj</code> you'll find the followin
     ((righto y x l))))
 
 (defn zebrao [hs]
-  (all
-   (== [_ _ [_ _ 'milk _ _] _ _] hs)                         
-   (firsto hs ['norwegian _ _ _ _])                         
-   (nexto ['norwegian _ _ _ _] [_ _ _ _ 'blue] hs)       
-   (righto [_ _ _ _ 'ivory] [_ _ _ _ 'green] hs)         
-   (membero ['englishman _ _ _ 'red] hs)                    
-   (membero [_ 'kools _ _ 'yellow] hs)                      
-   (membero ['spaniard _ _ 'dog _] hs)                      
-   (membero [_ _ 'coffee _ 'green] hs)                      
-   (membero ['ukrainian _ 'tea _ _] hs)                     
-   (membero [_ 'lucky-strikes 'oj _ _] hs)                  
-   (membero ['japanese 'parliaments _ _ _] hs)              
-   (membero [_ 'oldgolds _ 'snails _] hs)                   
-   (nexto [_ _ _ 'horse _] [_ 'kools _ _ _] hs)          
-   (nexto [_ _ _ 'fox _] [_ 'chesterfields _ _ _] hs)))
+  (macro/symbol-macrolet [_ (lvar)]
+    (all
+     (== [_ _ [_ _ 'milk _ _] _ _] hs)                         
+     (firsto hs ['norwegian _ _ _ _])                         
+     (nexto ['norwegian _ _ _ _] [_ _ _ _ 'blue] hs)       
+     (righto [_ _ _ _ 'ivory] [_ _ _ _ 'green] hs)         
+     (membero ['englishman _ _ _ 'red] hs)                    
+     (membero [_ 'kools _ _ 'yellow] hs)                      
+     (membero ['spaniard _ _ 'dog _] hs)                      
+     (membero [_ _ 'coffee _ 'green] hs)                      
+     (membero ['ukrainian _ 'tea _ _] hs)                     
+     (membero [_ 'lucky-strikes 'oj _ _] hs)                  
+     (membero ['japanese 'parliaments _ _ _] hs)              
+     (membero [_ 'oldgolds _ 'snails _] hs)                   
+     (nexto [_ _ _ 'horse _] [_ 'kools _ _ _] hs)          
+     (nexto [_ _ _ 'fox _] [_ 'chesterfields _ _ _] hs))))
 ```
 
 That is the entirety of the program. Let's run it: