code: def summarize(self, fields=None, context_len=None, num_frags=None, sep=None):
          
          args = ['SUMMARIZE']
          fields = self._mk_field_list(fields)
          if fields:
              args += ['FIELDS', str(len(fields))] + fields
  
          if context_len is not None:
              args += ['LEN', str(context_len)]
          if num_frags is not None:
              args += ['FRAGS', str(num_frags)]
          if sep is not None:
              args += ['SEPARATOR', sep]
  
          self._summarize_fields = args
          return self
docs: Return an abridged format of the field, containing only the segments of
          the field which contain the matching term(s).
  
          If `fields` is specified, then only the mentioned fields are
          summarized; otherwise all results are summarized.
  
          Server side defaults are used for each option (except `fields`) if not specified
  
          - **fields** List of fields to summarize. All fields are summarized if not specified
          - **context_len** Amount of context to include with each fragment
          - **num_frags** Number of fragments per document
          - **sep** Separator string to separate fragments