code: function arity (n, fn) {
    switch (n) {
      case 0: return function () { return fn.apply(null, arguments) }
      case 1: return function (a0) { return fn.apply(null, arguments) }
      case 2: return function (a0, a1) { return fn.apply(null, arguments) }
      case 3: return function (a0, a1, a2) { return fn.apply(null, arguments) }
      case 4: return function (a0, a1, a2, a3) { return fn.apply(null, arguments) }
      case 5: return function (a0, a1, a2, a3, a4) { return fn.apply(null, arguments) }
      case 6: return function (a0, a1, a2, a3, a4, a5) { return fn.apply(null, arguments) }
      case 7: return function (a0, a1, a2, a3, a4, a5, a6) { return fn.apply(null, arguments) }
      case 8: return function (a0, a1, a2, a3, a4, a5, a6, a7) { return fn.apply(null, arguments) }
      default: throw new Error('First argument to _arity must be a non-negative integer no greater than eight')
    }
  }
docs: Function Functions