public virtual object this[ 
   string key
]; {get; set;}

//Base class for entities and relationships
//(including documents and provenance)
public void ProcessGraphNamedObjectValue(
  KnowledgeGraphNamedObjectValue kg_named_obj_val)
{
  if (kg_named_obj_val is KnowledgeGraphEntityValue kg_entity)
  {
    var label = kg_entity.GetLabel();
    //TODO - use label
  }
  else if (kg_named_obj_val is KnowledgeGraphRelationshipValue kg_rel)
  {
    var has_entity_ids = kg_rel.GetHasRelatedEntityIDs();
    if (kg_rel.GetHasRelatedEntityIDs())
    {
      var origin_id = kg_rel.GetOriginID();
      var dest_id = kg_rel.GetDestinationID();
      //TODO - use ids
    }
  }
  var id = kg_named_obj_val.GetID();
  var oid = kg_named_obj_val.GetObjectID();
  //Note: Typename corresponds to the name of the feature class or table
  //in the relational gdb model -and- to the name of the KnowledgeGraphNamedObjectType
  //in the knowledge graph data model
  var type_name = kg_named_obj_val.GetTypeName();
  //TODO use id, object id, etc.
}

//Object values include entities, relationships, and anonymous objects
public void ProcessGraphObjectValue(KnowledgeGraphObjectValue kg_obj_val)
{
  switch (kg_obj_val)
  {
    case KnowledgeGraphEntityValue kg_entity:
      ProcessGraphNamedObjectValue(kg_entity);
      break;
    case KnowledgeGraphRelationshipValue kg_rel:
      ProcessGraphNamedObjectValue(kg_rel);
      break;
    default:
      //Anonymous objects
      break;
  }
  //graph object values have a set of properties (equivalent
  //to a collection of key/value pairs)
  var keys = kg_obj_val.GetKeys();
  foreach (var key in keys)
    ProcessKnowledgeGraphRowValue(kg_obj_val[key]);//Recurse
}

//Process a KnowledgeGraphValue from a query or search
public void ProcessGraphValue(KnowledgeGraphValue kg_val)
{
  switch (kg_val)
  {
    case KnowledgeGraphPrimitiveValue kg_prim:
      //KnowledgeGraphPrimitiveValue not currently used in
      //query and search 
      ProcessKnowledgeGraphRowValue(kg_prim.GetValue());//Recurse
      return;
    case KnowledgeGraphArrayValue kg_array:
      var count = kg_array.GetSize();
      //Recursively process each value in the array
      for (ulong i = 0; i < count; i++)
        ProcessKnowledgeGraphRowValue(kg_array[i]);//Recurse
      return;
    case KnowledgeGraphPathValue kg_path:
      //Entities
      var entity_count = kg_path.GetEntityCount();
      //Recursively process each entity value in the path
      for (ulong i = 0; i < entity_count; i++)
        ProcessGraphObjectValue(kg_path.GetEntity(i));//Recurse

      //Recursively process each relationship value in the path
      var relate_count = kg_path.GetRelationshipCount();
      for (ulong i = 0; i < relate_count; i++)
        ProcessGraphObjectValue(kg_path.GetRelationship(i));//Recurse
      return;
    case KnowledgeGraphObjectValue kg_object:
      ProcessGraphObjectValue(kg_object);//Recurse
      return;
    default:
      var type_string = kg_val.GetType().ToString();
      System.Diagnostics.Debug.WriteLine(
        $"Unknown: '{type_string}'");
      return;
  }
}

//Process each value from the KnowledgeGraphRow array
public void ProcessKnowledgeGraphRowValue(object value)
{
  switch (value)
  {
    //Graph value?
    case KnowledgeGraphValue kg_val:
      var kg_type = kg_val.KnowledgeGraphValueType.ToString();
      System.Diagnostics.Debug.WriteLine(
        $"KnowledgeGraphValue: '{kg_type}'");
      ProcessGraphValue(kg_val);//Recurse
      return;
    //Primitive types...add additional logic as needed
    case System.DBNull dbn:
      System.Diagnostics.Debug.WriteLine("DBNull.Value");
      return;
    case string str:
      System.Diagnostics.Debug.WriteLine($"'{str}' (string)");
      return;
    case long l_val:
      System.Diagnostics.Debug.WriteLine($"{l_val} (long)");
      return;
    case int i_val:
      System.Diagnostics.Debug.WriteLine($"{i_val} (int)");
      return;
    case short s_val:
      System.Diagnostics.Debug.WriteLine($"{s_val} (short)");
      return;
    case double d_val:
      System.Diagnostics.Debug.WriteLine($"{d_val} (double)");
      return;
    case float f_val:
      System.Diagnostics.Debug.WriteLine($"{f_val} (float)");
      return;
    case DateTime dt_val:
      System.Diagnostics.Debug.WriteLine($"{dt_val} (DateTime)");
      return;
    case DateOnly dt_only_val:
      System.Diagnostics.Debug.WriteLine($"{dt_only_val} (DateOnly)");
      return;
    case TimeOnly tm_only_val:
      System.Diagnostics.Debug.WriteLine($"{tm_only_val} (TimeOnly)");
      return;
    case DateTimeOffset dt_tm_offset_val:
      System.Diagnostics.Debug.WriteLine(
        $"{dt_tm_offset_val} (DateTimeOffset)");
      return;
    case System.Guid guid_val:
      var guid_string = guid_val.ToString("B");
      System.Diagnostics.Debug.WriteLine($"'{guid_string}' (Guid)");
      return;
    case Geometry geom_val:
      var geom_type = geom_val.GeometryType.ToString();
      var is_empty = geom_val.IsEmpty;
      var wkid = geom_val.SpatialReference?.Wkid ?? 0;
      System.Diagnostics.Debug.WriteLine(
        $"geometry: {geom_type}, empty: {is_empty}, sr_wkid {wkid} (shape)");
      return;
    default:
      //Blob? Others?
      var type_str = value.GetType().ToString();
      System.Diagnostics.Debug.WriteLine($"Primitive: {type_str}");
      return;
  }
}

// ...submit query or search
//using (var kg_rc = kg.SubmitQuery(kg_qf)) {
//using (var kg_rc = kg.SubmitSearch(kg_sf)) {
//  ...wait for rows ...
//  while (await kg_rc.WaitForRowsAsync()) {
//   ...rows have been retrieved
//   while (kg_rc.MoveNext()) {
//     ...get the current KnowledgeGraphRow
//     using (var graph_row = kg_rc.Current) {
//        var val_count = (int)graph_row.GetCount();
//        for (int i = 0; i<val_count; i++)
//           ProcessKnowledgeGraphRowValue(graph_row[i]);