isinstance.xml Make the example workable and semantic (php#4903)

Author: mmalferov

reference/reflection/reflectionclass/isinstance.xml

@@ -48,20 +48,24 @@
     <programlisting role="php">
 <![CDATA[
 <?php
-// Example usage
-$class = new ReflectionClass('Foo');
 
-if ($class->isInstance($arg)) {
-    echo "Yes";
+class Foo {}
+
+$object = new Foo();
+
+$reflection = new ReflectionClass('Foo');
+
+if ($reflection->isInstance($object)) {
+    echo "Yes\n";
 }
 
 // Equivalent to
-if ($arg instanceof Foo) {
-    echo "Yes";
+if ($object instanceof Foo) {
+    echo "Yes\n";
 }
 
 // Equivalent to
-if (is_a($arg, 'Foo')) {
+if (is_a($object, 'Foo')) {
     echo "Yes";
 }
 ?>