//! What the planner hands each `jump_dest` instance.
//!
//! The unit throughout is **rows**, not operations: one `jump_dest` spans
//! `ceil(count/64) * ROWS_X_BLOCK` rows, so a segment boundary can land in the
//! middle of one. `chunks` says, per chunk, how many rows this segment takes and
//! how many to skip first; `last_chunk` marks where the segment ends and
//! `is_last_segment` feeds the air value of the same name.
use HashMap;
use ;