better repl message

main.py

@@ -397,12 +397,16 @@ def evaluate(expr):
 def repl(args, cost, lookup):
     import readline;
     
-    print("""
-Give a boolean expression using the variables 'w', 'x', 'y' and 'z'.
-Operations: not ('!'), or ('||'), and ('&&').
-Extended operations: nor ('!|'), orn ('|!'), nand ('!&'), andn ('&!'), xor ('!='),
-Extended operations: nxor ('==')
-    """);
+    print("Give a boolean expression using the variables 'w', 'x', 'y' and 'z'.");
+    print("Operations: not ('!'), or ('||'), and ('&&').""");
+    
+    print();
+    
+    if args.extended_operators:
+        print("Extended operations: nor ('!|'), orn ('|!'), nand ('!&'), ");
+        print("andn ('&!'), xor ('!='), and nxor ('==')");
+    
+        print();
     
     # print(f'I can do anything in {max(cost.values())} operations.')
     # print();
@@ -414,7 +418,11 @@ Extended operations: nxor ('==')
             line = input(">>> ");
         except EOFError:
             return;
-            
+        
+        line = line.strip();
+        
+        if not line: continue;
+        
         truthtable = evaluate(parse(parser, line));
         
         if truthtable in lookup: