updated core to 7.58 (right after the site was hacked)

sites/all/modules/examples/block_example/block_example.install

@@ -0,0 +1,14 @@
+<?php
+/**
+ * @file
+ * Install, update and uninstall functions for the block_example module.
+ */
+
+/**
+ * Implements hook_uninstall().
+ *
+ * @ingroup block_example
+ */
+function block_example_uninstall() {
+  variable_del('block_example_string');
+}