     /// Used by indexType for type-safety
     private enum _IndexTypeNames: String, Codable {
         case text
+        case sphere2d
     }
     
     /// Used by indexType for type-safety

            switch try container.decode(_IndexTypeNames.self) {
            case .text:
                self = .text
            }
        }
    }
    
    case ascending, descending
    case text
    
    /// Internal helper that translates the index type to a primitive
    var primitive: Primitive {

            return -1 as Int32
        case .text:
            return "text"
        case .sphere2d:
            return "2dsphere"
        }
    }
    
