FOR ... IN statement is a control structure that executes a block of statements for all elements of an associative array.
FOR <element> IN <associative_array> <statements>... NEXT
Before processing the block of statements, <element> variable takes value of the next element of <associative_array>.
Another syntax of FOR ... IN statement allows to execute a block of statements for hash codes identifying all elements of an associative array:
FOR <key> IN <associative_array> KEYS <statements>... NEXT
m := map() m:qwer := 12 m:asdf := "hello" for member in m ? member next // 12 // hello for key in m keys ? key,m[key] next // 304733034 12 // 1190707477 hello