define [ ] ---- iter first last seek-lt a seek-lt z seek-ge a seek-ge z ---- . . . . . . define [ a.SET.1-b.SET.2 ] ---- iter last ---- 000001:[a#1,1-b#2,1] iter first next prev prev ---- 000001:[a#1,1-b#2,1] . 000001:[a#1,1-b#2,1] . iter seek-ge a seek-ge b seek-ge c ---- 000001:[a#1,1-b#2,1] 000001:[a#1,1-b#2,1] . iter seek-lt a seek-lt b seek-lt z ---- . 000001:[a#1,1-b#2,1] 000001:[a#1,1-b#2,1] define [ b.SET.1-c.SET.2 ] ---- iter seek-ge a seek-ge d seek-lt a seek-lt z ---- 000001:[b#1,1-c#2,1] . . 000001:[b#1,1-c#2,1] define a.SET.1-b.SET.2 [ c.SET.3-d.SET.4 e.SET.5-f.SET.6 ] g.SET.7-h.SET.8 ---- iter first prev last next ---- 000002:[c#3,1-d#4,1] . 000003:[e#5,1-f#6,1] . iter seek-ge a seek-ge b seek-ge c seek-ge h prev ---- 000002:[c#3,1-d#4,1] 000002:[c#3,1-d#4,1] 000002:[c#3,1-d#4,1] . 000003:[e#5,1-f#6,1] iter seek-lt b next seek-lt a next seek-lt z ---- . 000002:[c#3,1-d#4,1] . 000002:[c#3,1-d#4,1] 000003:[e#5,1-f#6,1] define a.SET.1-b.SET.2 c.SET.3-d.SET.4 e.SET.5-f.SET.6 g.SET.7-h.SET.8 [ ] ---- iter seek-ge cat seek-lt cat first last ---- . . . .