@Override
      public void beforeExpressionPush(@NotNull DfaValue value,
                                       @NotNull PsiExpression expression,
                                       @NotNull DfaMemoryState state) {
        if (expression == expr) {
          myVisited = true;
          myNullability = myNullability.unite(DfaNullability.fromDfType(state.getDfType(value)));
        }
      }
@Override
      public void beforeExpressionPush(@NotNull DfaValue value,
                                       @NotNull PsiExpression expression,
                                       @NotNull DfaMemoryState state)