<\body> <\explain> >|expr-n> <|explain> Forms a tuple from the expressions until . <\explain> <|explain> Tests whether a given expression evaluates to a tuple. <\explain> <|explain> If is a tuple, then we return its arity. For instance, >> evaluates to >. <\explain> <|explain> Returns the element with index in . For instance, |1>> yields |1>. <\explain> <|explain> Return the subtuple of starting at position and ending at position (not included). For instance, |2|4>> evaluates to |2|4>. <\explain> >|expr-n> <|explain> This primitive may be used to concatenate several tuples until . For instance, |>> produces |>.