// Build a Hello World program graph using 
// System.CodeDom types.
public static CodeCompileUnit BuildHelloWorldGraph()
{
    // Create a new CodeCompileUnit to contain 
    // the program graph.
    CodeCompileUnit compileUnit = new CodeCompileUnit();

    // Declare a new namespace called Samples.
    CodeNamespace samples = new CodeNamespace("Samples");
    // Add the new namespace to the compile unit.
    compileUnit.Namespaces.Add(samples);

    // Add the new namespace import for the System namespace.
    samples.Imports.Add(new CodeNamespaceImport("System"));

    // Declare a new type called Class1.
    CodeTypeDeclaration class1 = new CodeTypeDeclaration("Class1");
    // Add the new type to the namespace type collection.
    samples.Types.Add(class1);

    // Declare a new code entry point method.
    CodeEntryPointMethod start = new CodeEntryPointMethod();

    // Create a type reference for the System.Console class.
    CodeTypeReferenceExpression csSystemConsoleType = new CodeTypeReferenceExpression("System.Console");

    // Build a Console.WriteLine statement.
    CodeMethodInvokeExpression cs1 = new CodeMethodInvokeExpression(
        csSystemConsoleType, "WriteLine",
        new CodePrimitiveExpression("Hello World!"));

    // Add the WriteLine call to the statement collection.
    start.Statements.Add(cs1);

    // Build another Console.WriteLine statement.
    CodeMethodInvokeExpression cs2 = new CodeMethodInvokeExpression(
        csSystemConsoleType, "WriteLine",
        new CodePrimitiveExpression("Press the Enter key to continue."));

    // Add the WriteLine call to the statement collection.
    start.Statements.Add(cs2);

    // Build a call to System.Console.ReadLine.
    CodeMethodInvokeExpression csReadLine = new CodeMethodInvokeExpression(
        csSystemConsoleType, "ReadLine");

    // Add the ReadLine statement.
    start.Statements.Add(csReadLine);

    // Add the code entry point method to
    // the Members collection of the type.
    class1.Members.Add(start);

    return compileUnit;
}