flow like the river

BACK_BACK/node_modules/graphql/jsutils/promiseReduce.mjs

@@ -0,0 +1,16 @@
+import isPromise from "./isPromise.mjs";
+/**
+ * Similar to Array.prototype.reduce(), however the reducing callback may return
+ * a Promise, in which case reduction will continue after each promise resolves.
+ *
+ * If the callback does not return a Promise, then this function will also not
+ * return a Promise.
+ */
+
+export default function promiseReduce(values, callback, initialValue) {
+  return values.reduce(function (previous, value) {
+    return isPromise(previous) ? previous.then(function (resolved) {
+      return callback(resolved, value);
+    }) : callback(previous, value);
+  }, initialValue);
+}