docs: def index_list(self):
          '''
          Lists indices
          '''
          request = self.session
          url = 'http://%s:%s/_cluster/state/' % (self.host, self.port)
          response = request.get(url)
          if request.status_code==200:
              return response.get('metadata',{}).get('indices',{}).keys()
          else:
              return response