The equality function for fanouts.

v ~hash_size ~entry_size n creates a fan_out for an index with hash_size and entry_size, containing n elements.

nb_fans t is the number of fans in t.

search t hash is the interval of offsets containing hash, if present.

update t hash off updates t so that hash is registered to be at offset off.

Finalizes the update of the fanout. This is mandatory before any search query.

exported_size t is the size of export t. This does not actually compute the encoding of t.

export t is a string encoded form of t.

import ~hash_size buf decodes buf such that import ~hash_size (export t) = t if t was initially created with ~hash_size.