MACHIN

33/node_modules/assert-never/README.md

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+# Assert Never [![npm version][npm-image]][npm-url]
+
+Helper function for [exhaustive checks][exhaustive-checks] of discriminated
+unions in TypeScript.
+
+## Installation
+
+```
+npm install --save assert-never
+```
+
+## Usage
+
+```ts
+import {assertNever} from "assert-never";
+
+type A = {type: 'a'};
+type B = {type: 'b'};
+type Union = A | B;
+
+function doSomething(arg: Union) {
+  if (arg.type === 'a') {
+    return something;
+  }
+
+  if (arg.type === 'b') {
+    return somethingElse;
+  }
+
+  // TS will error if there are other types in the union
+  // Will throw an Error when called at runtime. Use `assertNever(arg, true)`
+  // instead to fail silently.
+  return assertNever(arg);
+}
+```
+
+[npm-image]: https://badge.fury.io/js/assert-never.svg
+[npm-url]: https://badge.fury.io/js/assert-never
+[exhaustive-checks]: https://basarat.gitbooks.io/typescript/docs/types/discriminated-unions.html#exhaustive-checks