Setting filter after object is instantiated?

[AcidRaZor]

I have this:

$prosperentApi = new Prosperent_Api();
$prosperentApi->set_api_key($api_key);
??
$prosperentApi->fetchTrends();
$prosperentApi->getFacets($facet);
/*some code here*/ 

How could I set a filter (merchant/city/country etc) in place of the question marks after I've instantiated the prosperentApi object?

[AcidRaZor]

And there I go answering my own question a few seconds later:

$prosperentApi->set_filterMerchant($filter); //or whatever filter you'd like to use