diff --git a/ArgumentContainer.cs b/ArgumentContainer.cs
index 21bf6b7..c644cc4 100644
--- a/ArgumentContainer.cs
+++ b/ArgumentContainer.cs
@@ -110,6 +110,7 @@ namespace ln.types
 
         public bool Contains(string longName)
         {
+            if (longName != null)
             foreach (Argument argument in arguments)
             {
                 if (longName.Equals(argument.Long))
diff --git a/Extensions.cs b/Extensions.cs
index abbbc6e..e065ada 100644
--- a/Extensions.cs
+++ b/Extensions.cs
@@ -96,6 +96,12 @@ namespace ln.types
         }
 
 
+        public static byte[] ReadToEnd(this Stream stream)
+        {
+            MemoryStream memoryStream = new MemoryStream();
+            stream.CopyTo(memoryStream);
+            return memoryStream.ToArray();
+        }
 
         public static void WriteBytes(this Stream stream, byte[] bytes)
         {
diff --git a/io/ContentSource.cs b/io/ContentSource.cs
new file mode 100644
index 0000000..5afd664
--- /dev/null
+++ b/io/ContentSource.cs
@@ -0,0 +1,8 @@
+using System;
+namespace ln.types.io
+{
+    public interface ContentSource
+    {
+        byte[] Content { get; }
+    }
+}
diff --git a/io/FileStorage.cs b/io/FileStorage.cs
new file mode 100644
index 0000000..962b745
--- /dev/null
+++ b/io/FileStorage.cs
@@ -0,0 +1,19 @@
+using System;
+using System.IO;
+namespace ln.types.io
+{
+    public abstract class FileStorage
+    {
+        public FileStorage(string path)
+        {
+        }
+
+        public abstract string[] ListFiles();
+        public abstract string[] ListDirectories();
+
+        public abstract bool ContainsFile(string path);
+        public abstract bool ContainsDirectory(string path);
+
+        public virtual bool Contains(string path) => ContainsDirectory(path) || ContainsFile(path);
+    }
+}
diff --git a/io/WatchedFile.cs b/io/WatchedFile.cs
new file mode 100644
index 0000000..41f3e49
--- /dev/null
+++ b/io/WatchedFile.cs
@@ -0,0 +1,48 @@
+using System;
+using System.IO;
+namespace ln.types.io
+{
+    public class WatchedFile : IDisposable, ContentSource
+    {
+        public string FileName { get; private set; }
+        public event FileSystemEventHandler Changed;
+
+        FileSystemWatcher fileSystemWatcher;
+
+        public WatchedFile(String filename)
+        {
+            FileName = filename;
+            fileSystemWatcher = new FileSystemWatcher(filename);
+            fileSystemWatcher.Changed += FileSystemWatcher_Changed;
+        }
+
+        public byte[] Content
+        {
+            get
+            {
+                using (FileStream fs = new FileStream(FileName,FileMode.Open))
+                {
+                    return fs.ReadBytes((int)fs.Length);
+                }
+            }
+            set
+            {
+                using (FileStream fs = new FileStream(FileName, FileMode.OpenOrCreate, FileAccess.Write))
+                {
+                    fs.Position = 0;
+                    fs.WriteBytes(value);
+                }
+            }
+        }
+
+        void FileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
+        {
+            Changed?.Invoke(sender, e);
+        }
+
+        public void Dispose()
+        {
+            fileSystemWatcher.Dispose();
+        }
+    }
+}
diff --git a/ln.types.csproj b/ln.types.csproj
index b0af7cb..d1fe40f 100644
--- a/ln.types.csproj
+++ b/ln.types.csproj
@@ -132,6 +132,9 @@
     <Compile Include="Promise.cs" />
     <Compile Include="test\PromiseTests.cs" />
     <Compile Include="threads\TaskQueue.cs" />
+    <Compile Include="io\WatchedFile.cs" />
+    <Compile Include="io\ContentSource.cs" />
+    <Compile Include="io\FileStorage.cs" />
     <Compile Include="threads\SchedulingPool.cs" />
     <Compile Include="test\SchedulingPoolTests.cs" />
   </ItemGroup>
@@ -156,6 +159,7 @@
     <Folder Include="cache\" />
     <Folder Include="collections\" />
     <Folder Include="odb\ng\diff\" />
+    <Folder Include="io\" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\ln.logging\ln.logging.csproj">