code: def _extract_fields(self, line):
          
          acc = {}
          field_tokens = line.split("\t")
          for field_token in field_tokens:
              kv_tokens = field_token.split('::')
              if len(kv_tokens) == 2:
                  (key, value) = kv_tokens
                  acc[key] = value
  
          return acc
docs: Extract the key/value fields from a line of performance data