How to use the @microsoft/web-library-build.setConfig function in @microsoft/web-library-build

// Copy fabric-core to dist to be published with fabric-react.
build.postCopy.setConfig({
  shouldFlatten: false,
  copyTo: {
    [path.join(distFolder, 'sass')]: [
      'node_modules/office-ui-fabric-core/dist/sass/**/*.*'
    ],
    [path.join(distFolder, 'css')]: [
      'node_modules/office-ui-fabric-core/dist/css/**/*.*'
    ]
  }
});

// Produce AMD bits in lib-amd on production builds.
if (isProduction || isNuke) {
  build.setConfig({
    libAMDFolder: path.join(packageFolder, 'lib-amd')
  });
}

// Short aliases for subtasks.
build.task('webpack', build.webpack);
build.task('tslint', build.tslint);
build.task('ts', build.typescript);
build.task('sass', build.sass);

// initialize tasks.
build.initialize(gulp);

'use strict';

let path = require('path');
let build = require('@microsoft/web-library-build');

build.sass.setConfig({ useCSSModules: true });
build.webpack.setConfig({ configPath: null });

build.setConfig({
  libAMDFolder: path.join(build.getConfig().packageFolder, 'lib-amd'),
  libES6Folder: path.join(build.getConfig().packageFolder, 'lib-es6')
});

build.preCopy.cleanMatch = ['src/preCopyTest.ts'];

build.initialize(require('gulp'));