src/cli/util.js/listDifferent
function listDifferent(context, input, options, filename) {
  if (!context.argv.check && !context.argv["list-different"]) {
    return;
  }

  try {
    if (!options.filepath && !options.parser) {
      throw new errors.UndefinedParserError(
        "No parser and no file path given, couldn't infer a parser."
      );
    }
    if (!prettier.check(input, options)) {
      if (!context.argv.write) {
        context.logger.log(filename);
        process.exitCode = 1;
      }
    }
  } catch (error) {
    context.logger.error(error.message);
  }

  return true;
}