code: public <T> Collection<T> filterNones
              (final Collection<Optional<T>> c)
          {
          final Collection<T> result = new LinkedList<T> ();
          
          final OptionalVisitor<Void,T> visitor = new OptionalVisitor<Void,T> ()
              {
              public Void visitNone
                      (final None<T> none)
                  {
                  // Do nothing.
                  return null;
                  }
              
              public Void visitSome
                      (final Some<T> some)
                  {
                  result.add (some.object ());
                  return null;
                  }
              };
          
          for (final Optional<T> current : c)
              {
              current.accept (visitor);
              }
          
          return result;
          }
docs: {@inheritDoc}