ydb/yql/essentials/tests/s-expressions/suites/EquiJoin/SelfJoinLimit1.yql

(
(let mr_source (DataSource 'yt 'plato))
(let x (Read! world mr_source (Key '('table (String 'Input))) '('key 'subkey 'value) '()))
(let world (Left! x))
(let table (Right! x))
(let table (Take table (Uint64 '2)))
(let join (EquiJoin '(table 'a) '(table 'b) 
'('Inner '"a" '"b" '('"a" '"key") '('"b" '"value") '()) '()))
(let res_sink (DataSink 'result))
(let world (Write! world res_sink (Key) join '('('type))))
(let world (Commit! world res_sink))
(return world)
)