title: The modifier 'static' is not valid for this item / Static interface error in c#
body: <p>How can we implement static methods in interface...?</p>
  
  <pre><code>public interface ICache
  {
    //Get item from cache
    static object Get(string pName);
  
    //Check an item exist in cache
    static bool Contains(string pName); 
  
    //Add an item to cache
    static void Add(string pName, object pValue);
  
    //Remove an item from cache
    static void Remove(string pName);
  }
  </code></pre>
  
  <p>The above interface throws error: <i>The modifier 'static' is not valid for this item</i></p>