if (pe != null) { addArrow(pe, e); }
if (pe != null) { addArrow(pe, e, "WAW hazard"); }
                private void onProperty(PropertyEvent e) {                    Object obj = e.getObject();                    Property prop = e.getProperty();                    Object arg = e.getArgument();                    addObjectDependency(e, arg);                    PropertyEvent pe = m_events.getLastEvent(obj, prop);                    if (pe != null) { addArrow(pe, e); }                    ObjectEvent objev = m_events.getLastEvent(obj);                    ObjectEvent argev = m_events.getLastEvent(arg);                    addLinkDependency(prop, objev, argev);                }