import edu.neu.ccs.demeter.dj.*;
Container = <contents> List.
List : N | E.
E = .
N = <first> Item <rest> List.
Item = <name> Ident <w> Weight.
Weight = <i> int.     

SummingVisitorDJ = <total> int extends Visitor.
CountingVisitorDJ = <total> int extends Visitor.
AverageVisitorDJ =
<cV> CountingVisitorDJ
<sV> SummingVisitorDJ
<current> float extends Visitor.
ResultVisitorDJ = <aV> AverageVisitorDJ extends Visitor.

Main = .