Some of these errors and their explanation:

• if a == None:
  Really common. None is a singleton, so you can (well, actually, have) to compare to it like ‘if a is None‘ or ‘if a is not None‘.
• if (condition):
  This is not really pythonic, if doesn’t take () around the condition in python, () purpose is grouping, you can use them in an if but only to clarify a really complex condition or similar stuff. Please don’t clutter code with unneeded characters.
• if len(list):
  This is a misunderstanding of Python way of things, any empty sequence (string, list, tuple) is False. So if you want to make sure a list is empty, just check if it’s False. Same for tuples, and in some ocassions for strings.
• if type(obj) is type(1):
  This is killing kittens, there’s a builtin function for this purpose, it’s called -surprise- isinstance(object, type). For example isinstance(123, int)

Read more about this and other conventions in PEP 8.