class Aws::Endpoints::Reference

def resolve(parameters, assigns)
  if parameters.class.singleton_class::PARAM_MAP.key?(@ref)
    member_name = parameters.class.singleton_class::PARAM_MAP[@ref]
    parameters[member_name]
  elsif assigns.key?(@ref)
    assigns[@ref]
  else
    raise ArgumentError,
          "Reference #{@ref} is not a param or an assigned value."
  end
end