code: def refresh_token
        if not @auth_details or
          not @auth_details.has_key? :refresh_token or
          not @auth_details[:refresh_token]
          raise '@auth_details[:refresh_token] does not contain a refresh token.'
        end
  
        access_token, expires_in, refresh_token =
          self.class.refresh_access_token @auth_details[:refresh_token]
        auth({
          :access_token => access_token,
          :refresh_token => refresh_token})
        [access_token, expires_in, refresh_token]
      end
docs: Refresh the current OAuth token using the current refresh token.