Move internal modules to “internal” folder.

.internal/baseGt.js

@@ -0,0 +1,14 @@
+/**
+ * The base implementation of `gt` which doesn't coerce arguments.
+ *
+ * @private
+ * @param {*} value The value to compare.
+ * @param {*} other The other value to compare.
+ * @returns {boolean} Returns `true` if `value` is greater than `other`,
+ *  else `false`.
+ */
+function baseGt(value, other) {
+  return value > other;
+}
+
+export default baseGt;