input: Write a function to handle and report errors when reading JSON data from a file. If the file does not exist, it should print a message indicating that the file does not exist. If the file is not in a valid JSON format, it should print a message indicating that the file is not in a valid JSON format.
  def read_data_from_json(filename):
      try:
          with open(filename, 'r') as f:
              data = json.load(f)
          return data
      except FileNotFoundError:
          print("The file specified does not exist.")
      except json.decoder.JSONDecodeError:
          print("The file specified is not in a valid JSON format.")
  assert read_data_from_json('nonexistent_file.json') == None
  assert read_data_from_json('invalid_json_file.json') == None
  assert read_data_from_json('valid_file.json') != None
output: def read_data_from_json(filename):
      try:
          with open(filename, 'r') as f:
              data = json.load(f)
          return data
      except FileNotFoundError:
          print("The file specified does not exist.")
      except json.decoder.JSONDecodeError:
          print("The file specified is not in a valid JSON format.")