Update app.py

app.py

@@ -174,7 +174,7 @@ class EnhancedBookGenerator:
             content_parts.append(generated)
             remaining_words -= len(generated.split())
             
-        return ' '.join(content_parts
+        return ' '.join(content_parts)
 
     def _enhance_content(self, content: str, facts: List[str]) -> str:
         """Enhance content with facts and structure"""