Register_raw
is like Register
except you get the whole update pipe to deal
with. This is useful if, e.g., your update_of_model
function can fail, so
that you'd like to filter items out from the result pipe.
Version_i : sig ... end
val rpc : (Version_i.query, Version_i.state, Version_i.update, Version_i.error) Rpc.State_rpc.t