code: def query_by_string(self, query, fields=None, limit=10, sampling=None):
          
          query = {
              "query_string": {
                  "query": query,
              }
          }
  
          return self._search(query, fields, limit, sampling)
docs: Returns raw rows that matches the given query string
  
          :arg query: query string to be run against Kibana log messages (ex. @message:"^PHP Fatal").
          :type fields list[str] or None
          :arg limit: the number of results (defaults to 10)
          :type sampling int or None
          :arg sampling: Percentage of results to be returned (0,100)