Update app.py

app.py

@@ -463,6 +463,8 @@ _BLOCKED_MODULES = frozenset({
 
 def _safe_import(name: str, globals_dict=None, locals_dict=None, fromlist=(), level=0):
     """Restricted import that only allows whitelisted modules."""
+    import builtins as _builtins
+    
     base_module = name.split('.')[0]
     
     if base_module in _BLOCKED_MODULES or name in _BLOCKED_MODULES:
@@ -471,7 +473,7 @@ def _safe_import(name: str, globals_dict=None, locals_dict=None, fromlist=(), le
     if base_module not in _ALLOWED_MODULES and name not in _ALLOWED_MODULES:
         raise SandboxViolationError(f"Import of '{name}' is not allowed. Allowed modules: {', '.join(sorted(_ALLOWED_MODULES))}")
     
-    return __builtins__["__import__"](name, globals_dict, locals_dict, fromlist, level)
+    return _builtins.__import__(name, globals_dict, locals_dict, fromlist, level)
 
 
 def _create_sandbox_builtins() -> Dict[str, Any]: