code: def test_update_implicit_index_dict_unset_with_null(self):
      data = [{"a": 1, "b": 2}, {"a": 2, "b": 3}]
      tbl = Table(data)
      view = tbl.view()
  
      # unset because "b" is null
      tbl.update({"__INDEX__": [0], "a": [3], "b": [None]})
      assert view.to_records() == [
          {"a": 3, "b": None},
          {"a": 2, "b": 3},
      ]
  
imports: import numpy
  import pyarrow
  import pandas
  from datetime import date, datetime
  from perspective.table import Table
  from pytest import mark
label_desc: Use image node_id 51 for calling the TestUpdate obj's underlying member method code with example usage: obj.test_update_implicit_index_dict_unset_with_null() without return types