for b in myDrives:
    my_lat = b['TheGpsLog'][0]['latitude']
my_long = b['TheGpsLog'][0]['longitude']
myGeolocCountry = DoReverseGeocode(lat_start, long_start)
b['geolocCountry'] = myGeolocCountry
python + pymongo: how to insert a new field on an existing document in mongo from a for loop