# File lib/fog/identity/openstack/v3/requests/list_groups.rb, line 6
          def list_groups(options = {})
            user_id = options.delete('user_id') || options.delete(:user_id)

            path = if user_id
                     "users/#{user_id}/groups"
                   else
                     "groups"
                   end

            request(
              :expects => [200],
              :method  => 'GET',
              :path    => path,
              :query   => options
            )
          end