pub const NODE_BASE: [NodeSlot; 7];Expand description
First node slot of each level inside a ring entry:
2K − 2K / 2^level. For 16 keys: 0, 16, 24, 28, 30.
NODE_LEVELS entries (seven in every batch-engine build) so that any
level up to KEY_BITS has a defined base; levels above
ROOT_LEVEL are never used.