def chain_enrichments!(agg)
      chain.keys.each do |e|
        enrichment = enrichment_cache(e)
        if enrichment.is_a? Audumbla::FieldEnrichment
          agg = do_field_enrichment(agg, enrichment, chain[e])
        else
          agg = do_basic_enrichment(agg, enrichment, chain[e])
        end
      end
    end
def chain_enrichments!(agg)
      chain.keys.each do |e|
        enrichment = enrichment_cache(e)
        if enrichment.is_a? Audumbla::FieldEnrichment
          agg = do_field_enrichment(agg, enrichment, chain[e])
        else
          agg = do_basic_enrichment(agg, enrichment, chain[e])
        end
      end
    end
Given an aggregation, take each enrichment specified by the `chain'
 given in our instantiation, and apply that enrichment, with the given
 options, modifying the aggregation in-place.