input: def read_data_from_json(filename: str) -> dict:
      """
      Reads data from a JSON file. If the file does not exist or is not in a valid JSON format,
      an appropriate error message is printed.
      >>> read_data_from_json('valid_file.json')
      {'key': 'value'}
      >>> read_data_from_json('nonexistent_file.json')
      The file specified does not exist.
      >>> read_data_from_json('invalid_file.json')
      The file specified is not in a valid JSON format.
      """
      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.")
output:     except Exception as e:
          print(f"An unexpected error occurred: {e}")