{
  "presets": [
    ["env", {
      "targets": {
        "browsers": ["last 2 versions"]
      },
      "exclude": ["transform-es2015-classes"],
      "useBuiltins": "usage",
      "loose": true
    }],
  ],
  "plugins": [
    "transform-object-rest-spread",
    ["transform-class-properties", {
      "spec": true
    }],
    ["transform-runtime", {
      "helpers": true,
      "polyfill": true,
      "regenerator": true
    }]
  ]
}