@Override
          public IterationMode next(final NodeType node) {
            if (!node.isVisible()) {
              return IterationMode.CONTINUE;
            }

            return callback.next(node);
          }
Iterates over all visible nodes in the graph.

@param callback Callback object that is invoked once for each visible node in the graph.
java/zylib/src/main/java/com/google/security/zynamics/zylib/gui/zygraph/functions/IteratorFunctions.java