.NET4.0 Code Conditions: Implementing Custom Rewriter

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace SampleApplication {

    public class RequiresException : Exception
    {
        public RequiresException(string message) { }
    }

    public class EnsuresException : Exception
    {

     public EnsuresException(string message) { }
    }

     public class InvariantException : Exception
    {
        public InvariantException(string message) { }
    }

 
    public class AssertException : Exception
    {
        public AssertException(string message) { }
    }
       

    public class AssumeException : Exception
    {

        public AssumeException(string message) { }
    }

     public static class CustomRewiterMethods
    {

        public static void Requires(bool cond, string msg)
        {
            if (!cond) throw new RequiresException(msg);
        }       

       
        public static void Ensures(bool cond, string msg)
        {
            if (!cond) throw new EnsuresException(msg);
        }       

        public static void Assert(bool cond, string msg)
        {
            if (!cond) throw new AssertException(msg);
        }

        public static void Assume(bool cond, string msg)
        {
            if (!cond) throw new AssumeException(msg);

        }

        public static void Invariant(bool cond, string msg)
        {
            if (!cond) throw new InvariantException(msg);
        }
    }
}