     // MARK: Resolution
     
     /**
-     Resolve a dependency registered with `key`.
+     Resolve a dependency.
      
      - returns: The resolved dependency or `nil` if it is not found.
      

        }
    }
    
    // The root filter method. All filters and existence checks ultimately end up here.
    private static func filter<K: Keyed & Hashable>(type: String?, name: AnyHashable?, container: AnyHashable?, metathunk: Metathunk? = nil) -> Set<K> {
        // Key matching is performed inside the lock (of course).
        let filtered: [K: Dependency] = lock.read {
            var filtered = Dictionary<K, Dependency>()
            for (key, dependency) in registrations {
                guard let key = K(key) else { continue }
                if let type = type, type != key.type { continue }
                if let name = name, name != key.name { continue }

    }
    
    /**
     Register the `resolution` block.
     
     - returns: The unique `Key<T>` for this registration.
     
