public static bool PhraseNodesAreEqual(PhraseNode pn1, PhraseNode pn2)
 {
     if (pn1.Size() != pn2.Size())
     {
         return(false);
     }
     for (int i = 0; i < pn1.Size(); i++)
     {
         if (!WordNodeTests.WordNodesAreEqual(pn1[i], pn2[i]))
         {
             return(false);
         }
     }
     return(true);
 }