input: def read_data_from_json(filename):
      """Reads data from a JSON file and returns it. If the file is not found or the
      file is not in a valid JSON format, appropriate error messages are printed.
      >>> read_data_from_json('nonexistent.json')
      The file specified does not exist.
      >>> read_data_from_json('invalid_format.json')
      The file specified is not in a valid JSON format.
      >>> read_data_from_json('valid_data.json')
      {'key': 'value'}
      """
      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}")