code: def increment(self, kwargs):
          
          index = None
  
          if kwargs:
              # index = hash(tuple(sorted(kwargs.items())))
              # Better keep something readable so we can output it.
              index = tuple(sorted(kwargs.items()))
  
          self[index] += 1
  
          return index
docs: Increments the counter for the given *kwargs*.
  
          The counter index is computed from *kwargs*.
  
          *kwargs* is an optional dict of vars captured by the
          :class:`filter.Filter` that match the log entry. An immutable version
          of *kwargs* is used as an index to keep track of several counters for
          the same :class:`rule.Rule`. It can be `None`.
  
          Returns the index of the updated counter.