Flat Trees are the core data structure that power Dat's Hypercore feeds. They
allow us to deterministically represent a tree structure as a vector. This is
particularly useful because vectors map elegantly to disk and memory.
Because Flat Trees are deterministic and pre-computed, there is no overhead
to using them. In effect this means that Flat Trees are a specific way of
indexing into a vector more than they are their own data structure. This makes
them uniquely efficient and convenient to implement in a wide range of