input: Write a function to parse a json-formatted string into a dictionary. The function should take a single string argument and return a dictionary. Use the json module's loads function for parsing. 
  
  def parse_json_to_dict(json_str):
      import json
      return json.loads(json_str)
  
  assert parse_json_to_dict('{"name": "John","age": 30,"address": {"city": "New York","state": "NY"}}') == {'name': 'John', 'age': 30, 'address': {'city': 'New York', 'state': 'NY'}}
  assert parse_json_to_dict('[]') == []
  assert parse_json_to_dict('{"key": null}') == {'key': None}
  assert parse_json_to_dict('{"numbers": [1, 2, 3]}') == {'numbers': [1, 2, 3]}
  assert parse_json_to_dict('null') == None
output: def parse_json_to_dict(json_str):
      import json
      return json.loads(json_str)