bug symfony#5607 Fix (sebastianbergmann)

This PR was submitted for the 2.8 branch but it was merged into the 2.7 branch instead (closes symfony#5607).

Discussion
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Fix

Commits
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d7f0a39 Fix

components/var_dumper/advanced.rst

@@ -145,7 +145,7 @@ Another option for doing the same could be::
     use Symfony\Component\VarDumper\Cloner\VarCloner;
     use Symfony\Component\VarDumper\Dumper\CliDumper;
 
-    cloner = new VarCloner();
+    $cloner = new VarCloner();
     $dumper = new CliDumper();
     $output = fopen('php://memory', 'r+b');