map_reduce question

mapf='''function() {
   ...: emit(this.admin1_code,       
   ...: {count:1, pop:this.population, elev:this.elevation});
   ...: }'''

 finalizef = '''function(key,doc) {
   ....: return {
   ....: count:doc.count,
   ....: pop: doc.pop,
   ....: mean_pop: doc.pop/doc.count,
   ....: mean_elev: doc.elev/doc.count};
   ....: }'''

 db.cities.reduce(
   ....: map=mapf,
   ....: reduce=reducef,
   ....: out='state_pop_elev',
   ....: query={'country_code': 'US'},
   ....: finalize=finalizef)

And here is a document from the db.state_pop_elev collection:
{u'_id': u'WY', u'value': {u'count': 6.0, u'mean_pop': 35860.833333333336, u'mean_elev': 1679.3333333333333, u'pop': 215165.0}}

I then try this:
cursor = db.state_pop_elev.find()

In [60]: for city in cursor.sort('mean_elev'):
....: print city