     return nil
   }
 
-  /// Gets the status message that was received
+  /// Gets a status message that was received
   ///
   /// - Returns: status message
   internal func receivedStatusMessage() -> String? {

    return nil
  }

  /// Gets the initial metadata that was received
  ///
  /// - Returns: metadata
  internal func receivedInitialMetadata() -> Metadata? {

    self.call = call
    self.operations = operations
    self.completion = completion
    // set tag to a unique value (per execution)
    let mutex = OperationGroupTagLock.sharedInstance.mutex
    mutex.lock()
    self.tag = OperationGroup.nextTag
    OperationGroup.nextTag += 1
    mutex.unlock()
    // create underlying observers and operations
    self.underlyingOperations = cgrpc_operations_create()
    cgrpc_operations_reserve_space_for_operations(self.underlyingOperations, Int32(operations.count))
    for operation in operations {
      let underlyingObserver = self.underlyingObserverForOperation(operation: operation)
      self.underlyingObservers.append(underlyingObserver)
      cgrpc_operations_add_operation(self.underlyingOperations, underlyingObserver)
    }
  }
