diff --git a/sarah/bot/base.py b/sarah/bot/base.py
index 159e77f..66e1da3 100644
--- a/sarah/bot/base.py
+++ b/sarah/bot/base.py
@@ -1,17 +1,17 @@
 # -*- coding: utf-8 -*-
 import abc
-from collections import OrderedDict
-from concurrent.futures import ThreadPoolExecutor, Future
-from functools import wraps
 import imp
 import importlib
+import inspect
 import logging
 import re
 import sys
+from collections import OrderedDict
+from concurrent.futures import ThreadPoolExecutor, Future
+from functools import wraps
 
 from apscheduler.schedulers.background import BackgroundScheduler
-
-from typing import Sequence, Optional, Callable, Union
+from typing import Optional, Callable, Union, Iterable
 
 from sarah.bot.types import PluginConfig, AnyFunction, CommandFunction
 from sarah.bot.values import Command, CommandMessage, UserContext, \
@@ -25,7 +25,7 @@ class Base(object, metaclass=abc.ABCMeta):
     __instances = {}
 
     def __init__(self,
-                 plugins: Sequence[PluginConfig] = None,
+                 plugins: Iterable[PluginConfig] = None,
                  max_workers: Optional[int] = None) -> None:
         if not plugins:
             plugins = ()
@@ -214,17 +214,19 @@ def wrapper(func: CommandFunction) -> None:
             def wrapped_function(*args, **kwargs) -> str:
                 return func(*args, **kwargs)
 
-            # Register only if bot is instantiated.
+            module = inspect.getmodule(func)
             self = cls.__instances.get(cls.__name__, None)
-            if self:
-                config = self.plugin_config.get(func.__module__, {})
+            # Register only if bot is instantiated.
+            if self and module:
+                module_name = module.__name__
+                config = self.plugin_config.get(module_name, {})
                 schedule_config = config.get('schedule', None)
                 if schedule_config:
                     # If command name duplicates, update with the later one.
                     # The order stays.
                     command = ScheduledCommand(name,
                                                wrapped_function,
-                                               func.__module__,
+                                               module_name,
                                                config,
                                                schedule_config)
                     try:
@@ -238,14 +240,14 @@ def wrapped_function(*args, **kwargs) -> str:
                 else:
                     logging.warning(
                         'Missing configuration for schedule job. %s. '
-                        'Skipping.' % func.__module__)
+                        'Skipping.' % module_name)
 
             # To ease plugin's unit test
             return wrapped_function
 
         return wrapper
 
-    def add_schedule_jobs(self, commands: Sequence[ScheduledCommand]) -> None:
+    def add_schedule_jobs(self, commands: Iterable[ScheduledCommand]) -> None:
         for command in commands:
             # self.add_schedule_job(command)
             job_function = self.generate_schedule_job(command)
@@ -273,14 +275,16 @@ def wrapper(func: CommandFunction) -> CommandFunction:
             def wrapped_function(*args, **kwargs) -> Union[str, UserContext]:
                 return func(*args, **kwargs)
 
-            # Register only if bot is instantiated.
+            module = inspect.getmodule(func)
             self = cls.__instances.get(cls.__name__, None)
-            if self:
-                config = self.plugin_config.get(func.__module__, {})
+            # Register only if bot is instantiated.
+            if self and module:
+                module_name = module.__name__
+                config = self.plugin_config.get(module_name, {})
                 # If command name duplicates, update with the later one.
                 # The order stays.
 
-                command = Command(name, func, func.__module__, config)
+                command = Command(name, func, module_name, config)
                 try:
                     # If command is already registered, updated it.
                     idx = [c.name for c in cls.__commands[cls.__name__]] \
diff --git a/sarah/bot/hipchat.py b/sarah/bot/hipchat.py
index 7a932dc..07355cc 100644
--- a/sarah/bot/hipchat.py
+++ b/sarah/bot/hipchat.py
@@ -1,32 +1,30 @@
 # -*- coding: utf-8 -*-
-from concurrent.futures import Future
 import logging
+from concurrent.futures import Future
 
 from sleekxmpp import ClientXMPP, Message
 from sleekxmpp.exceptions import IqTimeout, IqError
-from typing import Dict, Optional, Sequence, Callable
+from typing import Dict, Optional, Callable, Iterable
 
-from sarah.exceptions import SarahException
 from sarah.bot import Base, concurrent
-from sarah.bot.values import ScheduledCommand
 from sarah.bot.types import PluginConfig
+from sarah.bot.values import ScheduledCommand
+from sarah.exceptions import SarahException
 
 
 class HipChat(Base):
     def __init__(self,
-                 plugins: Sequence[PluginConfig]=None,
-                 jid: str='',
-                 password: str='',
-                 rooms: Sequence[str]=None,
-                 nick: str='',
-                 proxy: Dict=None,
-                 max_workers: int=None) -> None:
+                 plugins: Iterable[PluginConfig] = None,
+                 jid: str = '',
+                 password: str = '',
+                 rooms: Iterable[str] = None,
+                 nick: str = '',
+                 proxy: Dict = None,
+                 max_workers: int = None) -> None:
 
         super().__init__(plugins=plugins, max_workers=max_workers)
 
-        if not rooms:
-            rooms = []
-        self.rooms = rooms
+        self.rooms = rooms if rooms else []  # type: Iterable[str]
         self.nick = nick
         self.client = self.setup_xmpp_client(jid, password, proxy)
 
@@ -34,7 +32,7 @@ def generate_schedule_job(self,
                               command: ScheduledCommand) -> Optional[Callable]:
         # pop room configuration to leave minimal information for command
         # argument
-        rooms = command.schedule_config.pop('rooms', None)
+        rooms = command.schedule_config.pop('rooms', [])
         if not rooms:
             logging.warning(
                 'Missing rooms configuration for schedule job. %s. '
@@ -61,7 +59,7 @@ def connect(self) -> None:
     def setup_xmpp_client(self,
                           jid: str,
                           password: str,
-                          proxy: Dict=None) -> ClientXMPP:
+                          proxy: Dict = None) -> ClientXMPP:
         client = ClientXMPP(jid, password)
 
         if proxy:
diff --git a/sarah/bot/plugins/bmw_quotes.py b/sarah/bot/plugins/bmw_quotes.py
index 17267ac..5ffa547 100644
--- a/sarah/bot/plugins/bmw_quotes.py
+++ b/sarah/bot/plugins/bmw_quotes.py
@@ -2,10 +2,10 @@
 import random
 
 from typing import Dict
-from sarah.bot.values import CommandMessage
+
 from sarah.bot.hipchat import HipChat
 from sarah.bot.slack import Slack, SlackMessage, MessageAttachment
-
+from sarah.bot.values import CommandMessage
 
 # http://www.imdb.com/title/tt0105958/quotes
 quotes = ([('Eric', "So i said to myself, 'Kyle'"),
diff --git a/sarah/bot/plugins/echo.py b/sarah/bot/plugins/echo.py
index 598f620..9376958 100644
--- a/sarah/bot/plugins/echo.py
+++ b/sarah/bot/plugins/echo.py
@@ -1,8 +1,9 @@
 # -*- coding: utf-8 -*-
 from typing import Dict
-from sarah.bot.values import CommandMessage
+
 from sarah.bot.hipchat import HipChat
 from sarah.bot.slack import Slack
+from sarah.bot.values import CommandMessage
 
 
 # noinspection PyUnusedLocal
diff --git a/sarah/bot/plugins/hello.py b/sarah/bot/plugins/hello.py
index f4549eb..e1a0fd8 100644
--- a/sarah/bot/plugins/hello.py
+++ b/sarah/bot/plugins/hello.py
@@ -1,8 +1,8 @@
 # -*- coding: utf-8 -*-
 from typing import Dict
-from sarah.bot.values import CommandMessage, UserContext, InputOption
 
 from sarah.bot.hipchat import HipChat
+from sarah.bot.values import CommandMessage, UserContext, InputOption
 
 
 # noinspection PyUnusedLocal
diff --git a/sarah/bot/plugins/simple_counter.py b/sarah/bot/plugins/simple_counter.py
index 1e89bb5..13240f9 100644
--- a/sarah/bot/plugins/simple_counter.py
+++ b/sarah/bot/plugins/simple_counter.py
@@ -1,9 +1,9 @@
 # -*- coding: utf-8 -*-
 from typing import Dict
-from sarah.bot.values import CommandMessage
 
 from sarah.bot.hipchat import HipChat
 from sarah.bot.slack import Slack
+from sarah.bot.values import CommandMessage
 
 __stash = {'hipchat': {},
            'slack': {}}
diff --git a/sarah/bot/slack.py b/sarah/bot/slack.py
index 1ce60ee..63e8ead 100644
--- a/sarah/bot/slack.py
+++ b/sarah/bot/slack.py
@@ -1,24 +1,24 @@
 # -*- coding: utf-8 -*-
 # https://api.slack.com/rtm
-from concurrent.futures import Future
 import json
 import logging
+from concurrent.futures import Future
 
-from typing import Optional, Dict, Sequence, Callable
 import requests
+from typing import Optional, Dict, Callable, Iterable
 from websocket import WebSocketApp
-from sarah import ValueObject
 
-from sarah.exceptions import SarahException
+from sarah import ValueObject
 from sarah.bot import Base, concurrent
-from sarah.bot.values import RichMessage, ScheduledCommand
 from sarah.bot.types import PluginConfig
+from sarah.bot.values import RichMessage, ScheduledCommand
+from sarah.exceptions import SarahException
 
 
 class SlackClient(object):
     def __init__(self,
                  token: str,
-                 base_url: str='https://slack.com/api/') -> None:
+                 base_url: str = 'https://slack.com/api/') -> None:
         self.base_url = base_url
         self.token = token
 
@@ -36,8 +36,8 @@ def post(self, method, params=None, data=None) -> Dict:
     def request(self,
                 http_method: str,
                 method: str,
-                params: Dict=None,
-                data: Dict=None) -> Dict:
+                params: Dict = None,
+                data: Dict = None) -> Dict:
         http_method = http_method.upper()
         endpoint = self.generate_endpoint(method)
 
@@ -61,7 +61,7 @@ def request(self,
 
 
 class AttachmentField(ValueObject):
-    def __init__(self, title: str, value: str, short: bool=None):
+    def __init__(self, title: str, value: str, short: bool = None):
         pass
 
     def to_dict(self):
@@ -81,15 +81,15 @@ class MessageAttachment(ValueObject):
     def __init__(self,
                  fallback: str,
                  title: str,
-                 title_link: str=None,
-                 author_name: str=None,
-                 author_link: str=None,
-                 author_icon: str=None,
-                 fields: Sequence[AttachmentField]=None,
-                 image_url: str=None,
-                 thumb_url: str=None,
-                 pretext: str=None,
-                 color: str=None):
+                 title_link: str = None,
+                 author_name: str = None,
+                 author_link: str = None,
+                 author_icon: str = None,
+                 fields: Iterable[AttachmentField] = None,
+                 image_url: str = None,
+                 thumb_url: str = None,
+                 pretext: str = None,
+                 color: str = None):
         pass
 
     def to_dict(self):
@@ -109,16 +109,16 @@ def to_dict(self):
 
 class SlackMessage(RichMessage):
     def __init__(self,
-                 text: str=None,
-                 as_user: bool=True,
-                 username: str=None,
-                 parse: str="full",
-                 link_names: int=1,
-                 unfurl_links: bool=True,
-                 unfurl_media: bool=False,
-                 icon_url: str=None,
-                 icon_emoji: str=None,
-                 attachments: Sequence[MessageAttachment]=None):
+                 text: str = None,
+                 as_user: bool = True,
+                 username: str = None,
+                 parse: str = "full",
+                 link_names: int = 1,
+                 unfurl_links: bool = True,
+                 unfurl_media: bool = False,
+                 icon_url: str = None,
+                 icon_emoji: str = None,
+                 attachments: Iterable[MessageAttachment] = None):
         pass
 
     def __str__(self) -> str:
@@ -135,7 +135,7 @@ def to_dict(self):
 
         return params
 
-    def to_request_params(self):
+    def to_request_params(self) -> Dict:
         params = self.to_dict()
 
         if 'attachments' in params:
@@ -147,9 +147,9 @@ def to_request_params(self):
 
 class Slack(Base):
     def __init__(self,
-                 token: str='',
-                 plugins: Sequence[PluginConfig]=None,
-                 max_workers: int=None) -> None:
+                 token: str = '',
+                 plugins: Iterable[PluginConfig] = None,
+                 max_workers: int = None) -> None:
 
         super().__init__(plugins=plugins, max_workers=max_workers)
 
@@ -181,7 +181,7 @@ def connect(self) -> None:
 
     def generate_schedule_job(self,
                               command: ScheduledCommand) -> Optional[Callable]:
-        channels = command.schedule_config.pop('channels', None)
+        channels = command.schedule_config.pop('channels', [])
         if not channels:
             logging.warning(
                 'Missing channels configuration for schedule job. %s. '
@@ -193,7 +193,7 @@ def job_function() -> None:
             if isinstance(ret, SlackMessage):
                 for channel in channels:
                     # TODO Error handling
-                    data = dict({'channel': channel})
+                    data = {'channel': channel}
                     data.update(ret.to_request_params())
                     self.client.post('chat.postMessage', data=data)
             else:
@@ -280,7 +280,7 @@ def handle_message(self, content: Dict) -> Optional[Future]:
         ret = self.respond(content['user'], content['text'])
         if isinstance(ret, SlackMessage):
             # TODO Error handling
-            data = dict({'channel': content["channel"]})
+            data = {'channel': content["channel"]}
             data.update(ret.to_request_params())
             self.client.post('chat.postMessage', data=data)
         elif isinstance(ret, str):
@@ -300,7 +300,7 @@ def on_close(self, _: WebSocketApp) -> None:
     def send_message(self,
                      channel: str,
                      text: str,
-                     message_type: str='message') -> None:
+                     message_type: str = 'message') -> None:
         params = {'channel': channel,
                   'text': text,
                   'type': message_type,
diff --git a/sarah/bot/values/__init__.py b/sarah/bot/values/__init__.py
index d8a5002..337c8d0 100644
--- a/sarah/bot/values/__init__.py
+++ b/sarah/bot/values/__init__.py
@@ -1,7 +1,9 @@
 # -*- coding: utf-8 -*-
 import abc
 import re
-from typing import Union, Pattern, AnyStr, Callable, Sequence, Dict
+
+from typing import Union, Pattern, AnyStr, Callable, Dict, Iterable
+
 from sarah import ValueObject
 from sarah.bot.types import CommandFunction, CommandConfig
 
@@ -16,7 +18,6 @@ class InputOption(ValueObject):
     def __init__(self,
                  pattern: Union[Pattern, AnyStr],
                  next_step: Callable) -> None:
-
         if isinstance(pattern, str):
             self['pattern'] = re.compile(pattern)
 
@@ -36,7 +37,7 @@ class UserContext(ValueObject):
     def __init__(self,
                  message: Union[str, RichMessage],
                  help_message: str,
-                 input_options: Sequence[InputOption]) -> None:
+                 input_options: Iterable[InputOption]) -> None:
         pass
 
     def __str__(self):
@@ -51,7 +52,7 @@ def help_message(self) -> str:
         return self['help_message']
 
     @property
-    def input_options(self) -> Sequence[InputOption]:
+    def input_options(self) -> Iterable[InputOption]:
         return self['input_options']
 
 
@@ -103,6 +104,7 @@ def execute(self, *args) -> Union[UserContext, str]:
 
 
 class ScheduledCommand(Command):
+    # noinspection PyMissingConstructor
     def __init__(self,
                  name: str,
                  function: CommandFunction,
diff --git a/sarah/main.py b/sarah/main.py
index 3d441d0..c314980 100644
--- a/sarah/main.py
+++ b/sarah/main.py
@@ -1,21 +1,21 @@
 # -*- coding: utf-8 -*-
 
 import logging
-from multiprocessing import Process
 import os
+from multiprocessing import Process
 
-from typing import Dict, Sequence
 import yaml
+from typing import Dict, Iterable
 
 from sarah.bot.hipchat import HipChat
 from sarah.bot.slack import Slack
-from sarah.exceptions import SarahException
 from sarah.bot.types import Path
+from sarah.exceptions import SarahException
 
 
 class Sarah(object):
     def __init__(self,
-                 config_paths: Sequence[Path]) -> None:
+                 config_paths: Iterable[Path]) -> None:
 
         self.config = self.load_config(config_paths)
 
@@ -33,7 +33,7 @@ def start(self) -> None:
             slack_process.start()
 
     @staticmethod
-    def load_config(paths: Sequence[Path]) -> Dict:
+    def load_config(paths: Iterable[Path]) -> Dict:
         config = {}
 
         if not paths:
diff --git a/sarah/thread.py b/sarah/thread.py
index 07d9fa2..01283b7 100644
--- a/sarah/thread.py
+++ b/sarah/thread.py
@@ -1,12 +1,12 @@
 # -*- coding: utf-8 -*-
 # noinspection PyProtectedMember
-from concurrent.futures.thread import _WorkItem as WorkItem
-from concurrent.futures import Executor, Future
+import atexit
 import logging
-from queue import Queue
 import threading
 import weakref
-import atexit
+from concurrent.futures import Executor, Future
+from concurrent.futures.thread import _WorkItem as WorkItem
+from queue import Queue
 
 # Provide the same interface as ThreadPoolExecutor, but create only on thread.
 # Worker is created as daemon thread. This is done to allow the interpreter to
diff --git a/sarah/value_object.py b/sarah/value_object.py
index e147ce0..ec4c9ae 100644
--- a/sarah/value_object.py
+++ b/sarah/value_object.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from inspect import getfullargspec
+
 from typing import Any
 
 
diff --git a/setup.py b/setup.py
index ea2a984..f1ef85c 100644
--- a/setup.py
+++ b/setup.py
@@ -2,7 +2,6 @@
 import os
 
 from setuptools import setup, find_packages
-
 # noinspection PyPep8Naming
 from sarah import __name__ as PACKAGE_NAME
 from sarah import VERSION
diff --git a/tests/test_hipchat.py b/tests/test_hipchat.py
index 35e9623..8d3eb99 100644
--- a/tests/test_hipchat.py
+++ b/tests/test_hipchat.py
@@ -1,22 +1,22 @@
 # -*- coding: utf-8 -*-
 import concurrent
-from concurrent.futures import ALL_COMPLETED
-from time import sleep
 import logging
 import types
+from concurrent.futures import ALL_COMPLETED
+from time import sleep
 
 import pytest
+from assertpy import assert_that
+from mock import MagicMock, call, patch
 from sleekxmpp import ClientXMPP
-from sleekxmpp.test import TestSocket
-from sleekxmpp.stanza import Message
 from sleekxmpp.exceptions import IqTimeout, IqError
+from sleekxmpp.stanza import Message
+from sleekxmpp.test import TestSocket
 from sleekxmpp.xmlstream import JID
-from mock import MagicMock, call, patch
-from assertpy import assert_that
 
-from sarah.bot.values import UserContext, CommandMessage, Command
-from sarah.bot.hipchat import HipChat, SarahHipChatException
 import sarah.bot.plugins.simple_counter
+from sarah.bot.hipchat import HipChat, SarahHipChatException
+from sarah.bot.values import UserContext, CommandMessage, Command
 
 
 # noinspection PyProtectedMember
diff --git a/tests/test_hipchat_plugin.py b/tests/test_hipchat_plugin.py
index 958800b..91025ca 100644
--- a/tests/test_hipchat_plugin.py
+++ b/tests/test_hipchat_plugin.py
@@ -1,12 +1,13 @@
 # -*- coding: utf-8 -*-
 from assertpy import assert_that
-from sarah.bot.values import UserContext, CommandMessage
+
+from sarah.bot.plugins.bmw_quotes import hipchat_quote, hipchat_scheduled_quote
 from sarah.bot.plugins.echo import hipchat_echo
 from sarah.bot.plugins.hello import hipchat_hello, hipchat_user_feeling_good, \
     hipchat_user_feeling_bad
 from sarah.bot.plugins.simple_counter import hipchat_count, \
     hipchat_reset_count, reset_count
-from sarah.bot.plugins.bmw_quotes import hipchat_quote, hipchat_scheduled_quote
+from sarah.bot.values import UserContext, CommandMessage
 
 
 class TestEcho(object):
diff --git a/tests/test_main.py b/tests/test_main.py
index 8686483..338dfd0 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -1,8 +1,8 @@
 # -*- coding: utf-8 -*-
 import os
-from assertpy import assert_that
 
 import pytest
+from assertpy import assert_that
 
 from sarah.main import Sarah, SarahException
 
@@ -24,6 +24,6 @@ def test_non_existing_paths(self):
         with pytest.raises(SarahException) as e:
             Sarah(config_paths=non_existing_paths)
 
-        assert_that(str(e))\
-            .contains('Configuration file does not exist')\
+        assert_that(str(e)) \
+            .contains('Configuration file does not exist') \
             .contains(non_existing_paths[0])
diff --git a/tests/test_slack.py b/tests/test_slack.py
index d447a72..087eae2 100644
--- a/tests/test_slack.py
+++ b/tests/test_slack.py
@@ -2,9 +2,8 @@
 import logging
 import types
 
-from assertpy import assert_that
-
 import pytest
+from assertpy import assert_that
 from mock import patch, MagicMock, call
 
 import sarah
diff --git a/tests/test_slack_plugin.py b/tests/test_slack_plugin.py
index 2e175ba..f7821da 100644
--- a/tests/test_slack_plugin.py
+++ b/tests/test_slack_plugin.py
@@ -1,11 +1,12 @@
 # -*- coding: utf-8 -*-
 from assertpy import assert_that
-from sarah.bot.slack import SlackMessage
-from sarah.bot.values import CommandMessage
+
 from sarah.bot.plugins.bmw_quotes import slack_quote
 from sarah.bot.plugins.echo import slack_echo
 from sarah.bot.plugins.simple_counter import reset_count, slack_count, \
     slack_reset_count
+from sarah.bot.slack import SlackMessage
+from sarah.bot.values import CommandMessage
 
 
 class TestEcho(object):
diff --git a/tests/test_value_object.py b/tests/test_value_object.py
index d7ef5a1..ab2784e 100644
--- a/tests/test_value_object.py
+++ b/tests/test_value_object.py
@@ -1,9 +1,11 @@
 # -*- coding: utf-8 -*-
-from assertpy import assert_that
+import re
+
 import pytest
+from assertpy import assert_that
 from typing import Union, AnyStr, Pattern
+
 from sarah import ValueObject
-import re
 
 
 class TestInit(object):
@@ -28,7 +30,9 @@ def __init__(self, key1="spam", key2="ham", key3=None):
 
 class TestOverride(object):
     class MyValueWithInit(ValueObject):
-        def __init__(self, pattern: Union[Pattern, AnyStr]=None, key1="spam"):
+        def __init__(self,
+                     pattern: Union[Pattern, AnyStr, None],
+                     key1="spam") -> None:
             if isinstance(pattern, str):
                 self['pattern'] = re.compile(pattern)