class OAuth2::AccessToken

def configure_authentication!(opts)
  case options[:mode]
  when :header
    opts[:headers] ||= {}
    opts[:headers].merge!(headers)
  when :query
    opts[:params] ||= {}
    opts[:params][options[:param_name]] = token
  when :body
    opts[:body] ||= {}
    if opts[:body].is_a?(Hash)
      opts[:body][options[:param_name]] = token
    else
      opts[:body] += "&#{options[:param_name]}=#{token}"
    end
    # @todo support for multi-part (file uploads)
  else
    raise("invalid :mode option of #{options[:mode]}")
  end
end