sample-parent valid=1 all_valid=1 modified=1 last=1 sampled=1 delta=[7, 9] cycle=1
sample-left valid=1 all_valid=1 modified=0 last=0 sampled=1 cycle=1
sample-right valid=1 all_valid=1 modified=0 last=0 sampled=1 cycle=1
invalidate-parent valid=0 all_valid=0 modified=1 last=2 sampled=1 delta=[7, 9] cycle=2
invalidate-left valid=0 all_valid=0 modified=0 last=never sampled=1 cycle=2
invalidate-right valid=0 all_valid=0 modified=0 last=never sampled=1 cycle=2
