code: def merge(cls, components):
      
      # Note that action of the merged component is MODIFY until the first REPLACE is encountered.
      # This guarantees associativity.
      action = cls.MODIFY
      appends = []
      filters = []
      for component in components:
        if component._action is cls.REPLACE:
          appends = component._appends
          filters = component._filters
          action = cls.REPLACE
        elif component._action is cls.MODIFY:
          appends.extend(component._appends)
          filters.extend(component._filters)
        else:
          raise ParseError('Unknown action for list value: {}'.format(component.action))
      return cls(action, appends, filters)
docs: Merges components into a single component, applying their actions appropriately.
  
      This operation is associative:  M(M(a, b), c) == M(a, M(b, c)) == M(a, b, c).
  
      :param list components: an iterable of instances of ListValueComponent.
      :return: An instance representing the result of merging the components.
      :rtype: `ListValueComponent`