Initial import with skill sheet working

node_modules/@seald-io/nedb/lib/waterfall.js

@@ -0,0 +1,48 @@
+/**
+ * Responsible for sequentially executing actions on the database
+ * @private
+ */
+class Waterfall {
+  /**
+   * Instantiate a new Waterfall.
+   */
+  constructor () {
+    /**
+     * This is the internal Promise object which resolves when all the tasks of the `Waterfall` are done.
+     *
+     * It will change any time `this.waterfall` is called.
+     *
+     * @type {Promise}
+     */
+    this.guardian = Promise.resolve()
+  }
+
+  /**
+   *
+   * @param {AsyncFunction} func
+   * @return {AsyncFunction}
+   */
+  waterfall (func) {
+    return (...args) => {
+      this.guardian = this.guardian.then(() => {
+        return func(...args)
+          .then(result => ({ error: false, result }), result => ({ error: true, result }))
+      })
+      return this.guardian.then(({ error, result }) => {
+        if (error) return Promise.reject(result)
+        else return Promise.resolve(result)
+      })
+    }
+  }
+
+  /**
+   * Shorthand for chaining a promise to the Waterfall
+   * @param {Promise} promise
+   * @return {Promise}
+   */
+  chain (promise) {
+    return this.waterfall(() => promise)()
+  }
+}
+
+module.exports = Waterfall