code: function processFile(argv, inputPath, opt_outputPath) {
    // Setup output path.
    var outputPath = opt_outputPath;
    if (!opt_outputPath) {
      var ext = path.extname(inputPath);
      if (ext.length) {
        outputPath = inputPath.substr(0, inputPath.length - ext.length) +
            '.instrumented' + ext;
      } else {
        outputPath = inputPath + '.instrumented.js';
      }
    }
  
    var sourceCode = fs.readFileSync(inputPath).toString();
  
    // TODO(benvanik): support setting the module ID?
    var targetCode = transformCode(0, inputPath, sourceCode, argv);
  
    console.log('Writing ' + outputPath + '...');
    fs.writeFileSync(outputPath, targetCode);
    fs.chmodSync(outputPath, fs.statSync(inputPath).mode);
  }
docs: Processes a single input file.
  @param {!Object} argv Parsed arguments.
  @param {string} inputPath Input file path.
  @param {string=} opt_outputPath Output file path.