Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/node_modules/@redux-saga/is/dist/redux-saga-is.esm.js

@@ -0,0 +1,62 @@
+import { TASK, SAGA_ACTION, MULTICAST, IO } from '@redux-saga/symbols';
+
+var undef = function undef(v) {
+  return v === null || v === undefined;
+};
+var notUndef = function notUndef(v) {
+  return v !== null && v !== undefined;
+};
+var func = function func(f) {
+  return typeof f === 'function';
+};
+var number = function number(n) {
+  return typeof n === 'number';
+};
+var string = function string(s) {
+  return typeof s === 'string';
+};
+var array = Array.isArray;
+var object = function object(obj) {
+  return obj && !array(obj) && typeof obj === 'object';
+};
+var promise = function promise(p) {
+  return p && func(p.then);
+};
+var iterator = function iterator(it) {
+  return it && func(it.next) && func(it.throw);
+};
+var iterable = function iterable(it) {
+  return it && func(Symbol) ? func(it[Symbol.iterator]) : array(it);
+};
+var task = function task(t) {
+  return t && t[TASK];
+};
+var sagaAction = function sagaAction(a) {
+  return Boolean(a && a[SAGA_ACTION]);
+};
+var observable = function observable(ob) {
+  return ob && func(ob.subscribe);
+};
+var buffer = function buffer(buf) {
+  return buf && func(buf.isEmpty) && func(buf.take) && func(buf.put);
+};
+var pattern = function pattern(pat) {
+  return pat && (string(pat) || symbol(pat) || func(pat) || array(pat) && pat.every(pattern));
+};
+var channel = function channel(ch) {
+  return ch && func(ch.take) && func(ch.close);
+};
+var stringableFunc = function stringableFunc(f) {
+  return func(f) && f.hasOwnProperty('toString');
+};
+var symbol = function symbol(sym) {
+  return Boolean(sym) && typeof Symbol === 'function' && sym.constructor === Symbol && sym !== Symbol.prototype;
+};
+var multicast = function multicast(ch) {
+  return channel(ch) && ch[MULTICAST];
+};
+var effect = function effect(eff) {
+  return eff && eff[IO];
+};
+
+export { array, buffer, channel, effect, func, iterable, iterator, multicast, notUndef, number, object, observable, pattern, promise, sagaAction, string, stringableFunc, symbol, task, undef };