Move internal modules to “internal” folder.

.internal/listCacheDelete.js

@@ -0,0 +1,32 @@
+import assocIndexOf from './.internal/assocIndexOf.js';
+
+/** Built-in value references. */
+const splice = Array.prototype.splice;
+
+/**
+ * Removes `key` and its value from the list cache.
+ *
+ * @private
+ * @name delete
+ * @memberOf ListCache
+ * @param {string} key The key of the value to remove.
+ * @returns {boolean} Returns `true` if the entry was removed, else `false`.
+ */
+function listCacheDelete(key) {
+  const data = this.__data__;
+  const index = assocIndexOf(data, key);
+
+  if (index < 0) {
+    return false;
+  }
+  const lastIndex = data.length - 1;
+  if (index == lastIndex) {
+    data.pop();
+  } else {
+    splice.call(data, index, 1);
+  }
+  --this.size;
+  return true;
+}
+
+export default listCacheDelete;