code: def test_is_mangled(self):
      a = PackageMangler()
      b = PackageMangler()
      self.assertTrue(is_mangled(a.mangle("foo.bar")))
      self.assertTrue(is_mangled(b.mangle("foo.bar")))
  
      self.assertFalse(is_mangled("foo.bar"))
      self.assertFalse(is_mangled(demangle(a.mangle("foo.bar"))))
  
file_path: pytorch/test/package/test_mangling.py
imports: from io import BytesIO
  from torch.package import PackageExporter, PackageImporter
  from torch.package._mangling import demangle, get_mangle_prefix, is_mangled, PackageMangler
  from torch.testing._internal.common_utils import run_tests
label_desc: Use image node_id 4 for calling the TestMangling obj's underlying member method code with example usage: obj.test_is_mangled() without return types