Using Redis's command list for inspiration:

• Add the ability to store a BTreeMap of values, ordered by a score, in a single key within the key-value store. Redis uses an f64, but that feels inexact to me. Instead, I would prefer any Ord + Serialize type to work.
• Expose the functionality through the KeyValue trait.

Before working in-depth on this issue, please propose a hypothetical API using pseudo-code. Use the existing KeyValue trait's API for inspiration when designing this API.