code: def _find_usage_parameter_groups(self):
          
          num_groups = 0
  
          paginator = self.conn.get_paginator('describe_cache_parameter_groups')
          for page in paginator.paginate():
              for group in page['CacheParameterGroups']:
                  num_groups += 1
          self.limits['Parameter Groups']._add_current_usage(
              num_groups,
              aws_type='AWS::ElastiCache::ParameterGroup'
          )
docs: find usage for elasticache parameter groups