code: function write(destPath, options) {
    var debug = require('../debug').spawn('write');
  
    debug(function() { return 'destPath'; });
    debug(function() { return destPath; });
  
    debug(function() { return 'original options';});
    debug(function() { return options; });
  
    if (options === undefined && typeof destPath !== 'string') {
      options = destPath;
      destPath = undefined;
    }
    options = options || {};
  
    // set defaults for options if unset
    if (options.includeContent === undefined) {
      options.includeContent = true;
    }
    if (options.addComment === undefined) {
      options.addComment = true;
    }
    if (options.charset === undefined) {
      options.charset = 'utf8';
    }
  
    debug(function() { return 'derrived options'; });
    debug(function() { return options; });
  
    var internals = internalsInit(destPath, options);
  
    function sourceMapWrite(file, encoding, callback) {
      if (file.isNull() || !file.sourceMap) {
        this.push(file);
        return callback();
      }
  
      if (file.isStream()) {
        return callback(new Error(utils.PLUGIN_NAME + '-write: Streaming not supported'));
      }
  
      // fix paths if Windows style paths
      file.sourceMap.file = unixStylePath(file.relative);
  
      internals.setSourceRoot(file);
      internals.loadContent(file);
      internals.mapSources(file);
      internals.mapDestPath(file, this);
  
      this.push(file);
      callback();
    }
  
    return through.obj(sourceMapWrite);
  }
docs: Write the source map
  
  @param options options to change the way the source map is written