     }
     
     /**
-     Register the `resolution` block with the result type `T` and the parameter `P`.
+     Register the `resolution` block.
      
      - returns: The unique `Key<T>` for this registration.
      

    }
    
    /**
     Resolve a dependency registered with the given key.
     
     - returns: The resolved dependency or `nil` if it is not found.
     

     
     1. The `key` was not found.
     2. The `metadata` was not `==` to the metadata associated with `key`.
     3. The metadata was not of type `M`.q
    */
    public static func filter<K: Keyed & Hashable, M: Equatable>(key: K, metadata: M) -> Set<K> {
        return filter(key: key) { $0 == metadata }
