docs: def add_elasticache_replication_group(self, replication_group, region):
          ''' Adds an ElastiCache replication group to the inventory and index '''
  
          # Only want available clusters unless all_elasticache_replication_groups is True
          if not self.all_elasticache_replication_groups and replication_group['Status'] != 'available':
              return
  
          # Select the best destination address (PrimaryEndpoint)
          dest = replication_group['NodeGroups'][0]['PrimaryEndpoint']['Address']
  
          if not dest:
              # Skip clusters we cannot address (e.g. private VPC subnet)
              return
  
          # Add to index
          self.index[dest] = [region, replication_group['ReplicationGroupId']]
  
          # Inventory: Group by ID (always a group of 1)
          if self.group_by_instance_id:
              self.inventory[replication_group['ReplicationGroupId']] = [dest]
              if self.nested_groups:
                  self.push_group(self.inventory, 'instances', replication_group['ReplicationGroupId'])
  
          # Inventory: Group by region
          if self.group_by_region:
              self.push(self.inventory, region, dest)
              if self.nested_groups:
                  self.push_group(self.inventory, 'regions', region)
  
          # Inventory: Group by availability zone (doesn't apply to replication groups)
  
          # Inventory: Group by node type (doesn't apply to replication groups)
  
          # Inventory: Group by VPC (information not available in the current
          # AWS API version for replication groups
  
          # Inventory: Group by security group (doesn't apply to replication groups)
          # Check this value in cluster level
  
          # Inventory: Group by engine (replication groups are always Redis)
          if self.group_by_elasticache_engine:
              self.push(self.inventory, 'elasticache_redis', dest)
              if self.nested_groups:
                  self.push_group(self.inventory, 'elasticache_engines', 'redis')
  
          # Global Tag: all ElastiCache clusters
          self.push(self.inventory, 'elasticache_replication_groups', replication_group['ReplicationGroupId'])
  
          host_info = self.get_host_info_dict_from_describe_dict(replication_group)
  
          self.inventory["_meta"]["hostvars"][dest] = host_info