Move internal modules to “internal” folder.

.internal/arraySample.js

@@ -0,0 +1,15 @@
+import baseRandom from './.internal/baseRandom.js';
+
+/**
+ * A specialized version of `sample` for arrays.
+ *
+ * @private
+ * @param {Array} array The array to sample.
+ * @returns {*} Returns the random element.
+ */
+function arraySample(array) {
+  const length = array.length;
+  return length ? array[baseRandom(0, length - 1)] : undefined;
+}
+
+export default arraySample;