class_docstr: Test np <---> json
code: def test_normal(self):
      arr = np.random.rand(2, 4, 4)
      test_data = [
          "test",
          1,
          arr,
          [1, "a", [1, 2]],
          [arr] * 2,
          {"1": arr, "b": [arr]},
      ]
      s = to_json(test_data)
  
      ret = from_json(s)
  
      self.assertTrue((ret[2] == arr).all())
      self.assertTrue((ret[-1]["1"] == arr).all())
  
imports: import unittest
  import numpy
  from towhee.utils.serializer import to_json, from_json
label_desc: Use image node_id 1 for calling the TestNPFormat obj's underlying member method code with example usage: obj.test_normal() without return types