docstr: Test that __setitem__ can replace or insert a new element
  into a DatasetDict.
docstr_tok: ["Test","that","__setitem__","can","replace","or","insert","a","new","element","into","a","DatasetDict","."]
code: def test_setitem(self, value):
      """Test that __setitem__ can replace or insert a new element
      into a DatasetDict."""
  
      ds = DatasetDict(value)
      ds["a"] = 2
      value["a"] = 2
  
      assert ds == value
  
file_path: pennylane/tests/data/attributes/test_dict.py
imports: import pytest
  from pennylane.data.attributes import DatasetDict
label_desc: Use image node_id 4 for calling the TestDatasetDict obj's underlying member method code with example usage: obj.test_setitem(value) without return types