Suggestion: Allow merging of archetypes

Maybe I'm missing something, but it would be great to have a way to compose archetypes by merging existing ones rather than constructing them out of individual types. For example something like this:

Code (CSharp):

1.             var shipArch = EntityManager.CreateArchetype(
2.                 typeof(Position),
3.                 typeof(Heading),
4.                 typeof(MeshInstanceRenderer),
5.                 typeof(TransformMatrix),
6.                 typeof(Velocity),
7.                 typeof(Collider),
8.                 typeof(Rigidbody)
9.             );
10.            
11.             var playerArch = EntityManager.MergeArchetypes(
12.                 shipArch,
13.                 EntityManager.CreateArchetype(
14.                     typeof(Player),
15.                     typeof(PlayerInput)
16.                 )
17.             );

Archetypes seem to primarily be intended as a way to optimize memory layout rather than a dynamic class system, so the above suggestion may not be the way to implement it, but some way to create "mix-ins" out of sets of component types would be fantastic.