returns a pretty-printed string for specific features in a FeatureCollection

def only_specific_multisets(ent, multisets_to_show):
    '''
    returns a pretty-printed string for specific features in a FeatureCollection
    '''
    out_str = []
    for mset_name in multisets_to_show:
        for key, count in ent[mset_name].items():
            out_str.append( '%s - %d: %s' % (mset_name, count, key) )
    return '\n'.join(out_str)