// delete outgoing or ingoing link
 public void deleteLink(LinkModel deleteLinkModel, bool isOutgoing)
 {
     if (isOutgoing)
     {
         mOutgoingLinks.Remove(deleteLinkModel);
     }
     else
     {
         mIngoingLinks.Remove(deleteLinkModel);
     }
 }
 // add outgoing or ingoing link
 public void addLink(LinkModel newLinkModel, bool isOutgoing)
 {
     if (isOutgoing)
     {
         addOutgoingLink(newLinkModel);
     }
     else
     {
         addIngoingLink(newLinkModel);
     }
 }
 // add ingoing link
 public void addIngoingLink(LinkModel newIngoingLinkModel)
 {
     mIngoingLinks.Add(newIngoingLinkModel);
 }
 // add outgoing link
 public void addOutgoingLink(LinkModel newOutgoingLinkModel)
 {
     mOutgoingLinks.Add(newOutgoingLinkModel);
 }