code: function layerRequirements() {
    if (!this.options.layer) {
      return BbPromise.resolve();
    }
  
    this.serverless.cli.log('Packaging Python Requirements Lambda Layer...');
  
    return BbPromise.bind(this)
      .then(zipRequirements)
      .then(createLayers);
  }
docs: Creates a layer from the installed requirements.
  @return {Promise} the combined promise for requirements layer.