#vulnerable code 
                              @Test
  public void no_field() {
    ClassDef empty = parseClass(
      "class C: ",
      "  pass");
    assertThat(empty.classFields()).isEmpty();
    assertThat(empty.instanceFields()).isEmpty();

    ClassDef empty2 = parseClass(
      "class C:",
      "  def f(): pass");
    assertThat(empty2.classFields()).isEmpty();
    assertThat(empty2.instanceFields()).isEmpty();
  } 
                            #location 12 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @Test
  public void no_field() {
    ClassDef empty = parseClass(
      "class C: ",
      "  pass");
    assertThat(empty.classFields()).isEmpty();
    assertThat(empty.instanceFields()).isEmpty();
  }