code: def extract_result(response, action_name)
        method = @registry.get_method_signature(action_name)
        action = method[:output][:name].to_sym
        result = response.to_hash
        result = result[action] if result.include?(action)
        result = normalize_output(result, method)
        return result[:rval] || result
      end
docs: Instance initializer.
  
   Args:
    - registry: a registry that defines service
  
   Extracts the finest results possible for the given result. Returns the
   response itself in worst case (contents unknown).