Move internal modules to “internal” folder.

.internal/baseSample.js

@@ -0,0 +1,15 @@
+import arraySample from './.internal/arraySample.js';
+import values from './values.js';
+
+/**
+ * The base implementation of `sample`.
+ *
+ * @private
+ * @param {Array|Object} collection The collection to sample.
+ * @returns {*} Returns the random element.
+ */
+function baseSample(collection) {
+  return arraySample(values(collection));
+}
+
+export default baseSample;