Add supporting themes required for Lotusdocs

themes/hugo-mod-jslibs-dist/popperjs/package/lib/utils/uniqueBy.js

@@ -0,0 +1,11 @@
+export default function uniqueBy(arr, fn) {
+  var identifiers = new Set();
+  return arr.filter(function (item) {
+    var identifier = fn(item);
+
+    if (!identifiers.has(identifier)) {
+      identifiers.add(identifier);
+      return true;
+    }
+  });
+}