Move internal modules to “internal” folder.

.internal/baseRandom.js

@@ -0,0 +1,18 @@
+/* Built-in method references for those with the same name as other `lodash` methods. */
+const nativeFloor = Math.floor;
+const nativeRandom = Math.random;
+
+/**
+ * The base implementation of `random` without support for returning
+ * floating-point numbers.
+ *
+ * @private
+ * @param {number} lower The lower bound.
+ * @param {number} upper The upper bound.
+ * @returns {number} Returns the random number.
+ */
+function baseRandom(lower, upper) {
+  return lower + nativeFloor(nativeRandom() * (upper - lower + 1));
+}
+
+export default baseRandom;