-- Indexes in sequence a of last point of forward or reverse paths in graph.
-- Myers algorithm indexes by diagonal k which for negative is bad deopt in V8.
-- This package indexes by iF and iR which are greater than or equal to zero.
-- and also updates the index arrays in place to cut memory in half.
-- kF = 2 * iF - d
-- kR = d - 2 * iR

type Indexes = Array<number>
