input: Write a Python function to parse a JSON formatted string into a dictionary.
  assert parseJSONString('{"name": "John", "age": 30, "city": "New York"}') == {"name": "John", "age": 30, "city": "New York"}
  assert parseJSONString('{"a": 1, "b": 2, "c": 3}') == {"a": 1, "b": 2, "c": 3}
  assert parseJSONString('{"x": 10, "y": {"z": 20}}') == {"x": 10, "y": {"z": 20}}
output: import json
  
  def parseJSONString(json_string):
      return json.loads(json_string)