createMutex = () => {
  let token = true;
  return (f, g) => {
    if (token) {
      token = false;

      try {
        f();
      } finally {
        token = true;
      }
    } else if (g !== undefined) {
      g();
    }
  };
}
Creates a mutual exclude function with the following property:

```js
const mutex = createMutex()
mutex(() => {
  // This function is immediately executed
  mutex(() => {
    // This function is not executed, as the mutex is already active.
  })
})
```

@return {mutex} A mutual exclude function
@public