libsbmlcs.XMLNode.removeChild C# (CSharp) Method

        public XMLNode removeChild(long n)
        {
            IntPtr cPtr = libsbmlPINVOKE.XMLNode_removeChild(swigCPtr, n);
            XMLNode ret = (cPtr == IntPtr.Zero) ? null : new XMLNode(cPtr, true);
            return ret;
        }

 public void test_SyntaxChecker_validXHTML()
 {
     SBMLNamespaces NS24 = new  SBMLNamespaces(2,4);
       SBMLNamespaces NS31 = new  SBMLNamespaces(3,1);
       XMLToken toptoken;
       XMLNode topnode;
       XMLTriple toptriple = new  XMLTriple("notes", "", "");
       XMLToken token;
       XMLNode node;
       XMLTriple triple = new  XMLTriple("p", "", "");
       XMLAttributes att = new  XMLAttributes();
       XMLNamespaces ns = new  XMLNamespaces();
       ns.add( "http://www.w3.org/1999/xhtml", "");
       XMLToken tt = new  XMLToken("This is my text");
       XMLNode n1 = new XMLNode(tt);
       toptoken = new  XMLToken(toptriple,att);
       topnode = new XMLNode(toptoken);
       token = new  XMLToken(triple,att,ns);
       node = new XMLNode(token);
       node.addChild(n1);
       topnode.addChild(node);
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,null) == true );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS24) == true );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS31) == true );
       triple = new  XMLTriple("html", "", "");
       token = new  XMLToken(triple,att,ns);
       node = new XMLNode(token);
       node.addChild(n1);
       topnode.removeChild(0);
       topnode.addChild(node);
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,null) == true );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS24) == false );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS31) == true );
       triple = new  XMLTriple("html", "", "");
       ns.clear();
       token = new  XMLToken(triple,att,ns);
       node = new XMLNode(token);
       node.addChild(n1);
       topnode.removeChild(0);
       topnode.addChild(node);
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,null) == false );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS24) == false );
       assertTrue( SyntaxChecker.hasExpectedXHTMLSyntax(topnode,NS31) == false );
 }