$_name
$_name : string
Class Filter.
This function can be used to handle params for queries, filter
__construct(string $name, \Elastica\Query\AbstractQuery $filter = null)
| string | $name | the name of this aggregation | 
| \Elastica\Query\AbstractQuery | $filter | 
addAggregation(\Elastica\Aggregation\AbstractAggregation  $aggregation) : $this
                Add a sub-aggregation.
| \Elastica\Aggregation\AbstractAggregation | $aggregation | 
setFilter(\Elastica\Query\AbstractQuery  $filter) : $this
                Set the filter for this aggregation.
| \Elastica\Query\AbstractQuery | $filter |