A composite of many visitors. Any call to a method from Visitor will invoke each visitor in turn, and reverse the invocation order on a closing visit. i.e. with the list of visitors = [a,b,c] composite.visitDefault() would... call on the opening visit - a.visitDefault() then b.visitDefault() then c.visitDefault() call on the closing visit - c.visitDefault() then b.visitDefault() then a.visitDefault()