var typed = require("typed-function");

typed.addType({
  name: 'zero',
  test: function (x) {    return x === 0;  }
});

typed.addType({
  name: 'one',
  test: function (x) {    return x === 1;  }
});

const fib = typed({
  'zero': function (n) { return 0 },
  'one': function (n) { return 1 },
  'any': function (n) { return fib(n - 1) + fib(n - 2); }
});

document.body.innerHTML =
   new Array(20).fill().map(function (x,i) { return fib(i); });