pymongo 3.2 read_preference

Python 2.7.11 (default, Dec 26 2015, 17:47:15) 
[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from pymongo import *
>>> from time import sleep
>>> print version
3.2.2
>>> C = MongoClient("m0.lmfdb.xyz", replicaSet = "lmfdb0", read_preference = read_preferences.Secondary())
>>> sleep(1)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=None)
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30
>>> sleep(30)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=None)
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30
>>> C = MongoClient("m0.lmfdb.xyz", replicaSet = "lmfdb0", read_preference = read_preferences.Secondary(tag_sets=[{'dc':'us-central'}]))
>>> sleep(1)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=[{'dc': 'us-central'}])
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30
>>> sleep(30)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=[{'dc': 'us-central'}])
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30
>>> C = MongoReplicaSetClient("m0.lmfdb.xyz", replicaSet = "lmfdb0", read_preference = read_preferences.Secondary(tag_sets=[{'dc':'us-central'}]))
>>> sleep(1)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=[{'dc': 'us-central'}])
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30
>>> sleep(30)
>>> print C.address
(u'warwick.lmfdb.xyz', 37010)
>>> print C.primary
(u'warwick.lmfdb.xyz', 37010)
>>> print C.is_primary
True
>>> print C.read_preference
Secondary(tag_sets=[{'dc': 'us-central'}])
>>> print C.secondaries
set([(u'm1.lmfdb.xyz', 27017), ('m0.lmfdb.xyz', 27017)])
>>> print C.is_mongos
False
>>> print C.nodes
frozenset([(u'm1.lmfdb.xyz', 27017), (u'warwick.lmfdb.xyz', 37010), ('m0.lmfdb.xyz', 27017)])
>>> print C.server_selection_timeout
30