docs: function createSourceMapFile(opts) {
    return new File({
      cwd: opts.cwd,
      base: opts.base,
      path: opts.path,
      contents: new Buffer(JSON.stringify(opts.content)),
      stat: {
        isFile: function() {
          return true;
        },
        isDirectory: function() {
          return false;
        },
        isBlockDevice: function() {
          return false;
        },
        isCharacterDevice: function() {
          return false;
        },
        isSymbolicLink: function() {
          return false;
        },
        isFIFO: function() {
          return false;
        },
        isSocket: function() {
          return false;
        },
      },
    });
  }