docs: private static void removeDep(Collection<TypedDependency> list) {
      Set<GrammaticalRelation> prepRels = new HashSet<GrammaticalRelation>(EnglishGrammaticalRelations.getPreps());
      prepRels.addAll(EnglishGrammaticalRelations.getPrepsC());
      for (TypedDependency td1 : list) {
        if (prepRels.contains(td1.reln())) { // if we have a prep_ relation
          TreeGraphNode gov = td1.gov();
          TreeGraphNode dep = td1.dep();
  
          for (TypedDependency td2 : list) {
            if (td2.reln() == DEPENDENT && td2.gov() == gov && td2.dep() == dep) {
              td2.setReln(KILL);
            }
          }
        }
      }
  
      // now remove typed dependencies with reln "kill"
      for (Iterator<TypedDependency> iter = list.iterator(); iter.hasNext();) {
        TypedDependency td = iter.next();
        if (td.reln() == KILL) {
          if (DEBUG) {
            System.err.println("Removing duplicate relation: " + td);
          }
          iter.remove();
        }
      }
    }