def instantiate_callback(callback_file, callback_class, callback_type)
      require callback_file
      PaynetEasy::PaynetEasyApi::Callback.const_get(callback_class).new(callback_type)
    end
def instantiate_callback(callback_file, callback_class, callback_type)
      require callback_file
      PaynetEasy::PaynetEasyApi::Callback.const_get(callback_class).new(callback_type)
    end
Load callback class file and return new callback object

 @param    callback_file     [String]              Callback class file
 @param    callback_class    [String]              Callback class
 @param    callback_type     [String]              Callback type

 @return                     [CallbackPrototype]   Callback object