NewDataServer returns a new `DataServer` or an `error` if something occurs.

NewMessage returns a new `*Message`.

NewSlidingWindow returns a new `*SlidingWindow`.

DataServer is a `struct` used for gathering and forwarding `bully.Bully`s state.

Message is a `struct` used for communication between `bully.Bully`s and the `DataServer`.

SlidingWindow is a `struct` representing a node state over time.