code: def test_getitem_v1(self):
      fa = FieldArray(
          "y", [[1.1, 2.2, 3.3, 4.4, 5.5], [1.0, 2.0, 3.0, 4.0, 5.0]]
      )
      assert fa[0] == [1.1, 2.2, 3.3, 4.4, 5.5]
      ans = fa[[0, 1]]
      assert isinstance(ans, np.ndarray) == True
      assert isinstance(ans[0], np.ndarray) == True
      assert ans[0].tolist() == [1.1, 2.2, 3.3, 4.4, 5.5]
      assert ans[1].tolist() == [1, 2, 3, 4, 5]
      assert ans.dtype == np.float64
  
imports: import os
  import pytest
  import numpy
  from fastNLP.core.dataset import DataSet, FieldArray, Instance, ApplyResultException
  from fastNLP import logger
label_desc: Use image node_id 2 for calling the TestFieldArray obj's underlying member method code with example usage: obj.test_getitem_v1() without return types