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(Collect item-xpr (var xs ok-xpr ...) (var1 xs1 ok-xpr1 ...) ...)syntax

creates a new list by binding var to each element of the list xs in sequence, and if it passes the checks, ok-xpr ..., inserts the value of item-xpr into the result list. The qualifieres, (var xs ok-xpr ...), are processed sequentially from left to right, so that filters of a qualifier have access to the variables of qualifiers to its left.