code: function es5Plugins(){
      return [
        require('babel-plugin-check-es2015-constants'),
        require('babel-plugin-transform-es2015-arrow-functions'),
        require('babel-plugin-transform-es2015-block-scoped-functions'),
        require('babel-plugin-transform-es2015-block-scoping'),
        require('babel-plugin-transform-es2015-classes'),
        require('babel-plugin-transform-es2015-computed-properties'),
        require('babel-plugin-transform-es2015-destructuring'),
        require('babel-plugin-transform-es2015-duplicate-keys'),
        require('babel-plugin-transform-es2015-for-of'),
        require('babel-plugin-transform-es2015-function-name'),
        require('babel-plugin-transform-es2015-literals'),
        require('babel-plugin-transform-es2015-object-super'),
        require('babel-plugin-transform-es2015-parameters'),
        require('babel-plugin-transform-es2015-shorthand-properties'),
        require('babel-plugin-transform-es2015-spread'),
        require('babel-plugin-transform-es2015-sticky-regex'),
        require('babel-plugin-transform-es2015-template-literals'),
        require('babel-plugin-transform-es2015-typeof-symbol'),
        require('babel-plugin-transform-es2015-unicode-regex'),
        require('babel-plugin-transform-async-to-generator'),
        require('babel-plugin-transform-exponentiation-operator'),
        require('babel-plugin-transform-regenerator')
      ];
    }
docs: Add default transformations