>>> import pymongo
>>> pymongo.version
'3.3.0'
>>> pm = pymongo.MongoClient(host='/tmp/mongodb-20000.sock')
>>> pm
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/pymongo/mongo_client.py", line 909, in __repr__
    return ("MongoClient(%s)" % (self._repr_helper(),))
  File "/usr/local/lib/python2.7/dist-packages/pymongo/mongo_client.py", line 896, in _repr_helper
    for host, port in self._topology_settings.seeds]]
TypeError: %d format: a number is required, not NoneType

>>> pm.somedb.somecol.find_one()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.7/dist-packages/pymongo/collection.py", line 1014, in find_one
    for result in cursor.limit(-1):
  File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 1090, in next
    if len(self.__data) or self._refresh():
  File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 1012, in _refresh
    self.__read_concern))
  File "/usr/local/lib/python2.7/dist-packages/pymongo/cursor.py", line 905, in __send_message
    helpers._check_command_response(doc['data'][0])
  File "/usr/local/lib/python2.7/dist-packages/pymongo/helpers.py", line 205, in _check_command_response
    raise OperationFailure(msg % errmsg, code, response)
pymongo.errors.OperationFailure: not authorized on somedb to execute command { find: "somecol", filter: {}, limit: 1, singleBatch: true }