namespace System.Runtime.InteropServices
{
    public static class CollectionsMarshal
    {
        public static ref TValue GetValueRefOrAddDefault<TKey, TValue, TAlternateKey>(AlternateLookup<TAlternateKey> dictionary, TAlternateKey key, out bool exists)
            where TKey, notnull
            where TAlternateKey, notnull;
    }
}