TODO
Initially, we don't need to implement routines because realm package functions provide all the inter-realm functionality we need to implement rich smart contract programming systems. But later, for various reasons including long-running background jobs, and parallel concurrency, Gno will implement deterministic concurrency as well.
Determinism is supported by including a deterministic timestamp with each channel message as well as periodic heartbeat messages even with no sends, so that select/receive operations can behave deterministically even in the presence of multiple channels to select from.