All parameters and resulting values of all metabase operations are
structured in new types. The most popular scenarios for using operations are
moved to auxiliary functions.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
Implement Delete method on DB structure that adds deleted addresses to
tombstone index. Do not attach addresses from tombstone index to Select
result. Return error from Get method if address is presented in tombstone
index.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
