EP19 Provide Optional Behavior with Keyword Arguments

• Function argument can be secified by position or by keywrod.

• Keywords make it clear what the purpose of each argument is when it would be confusing with only positional arguments
• Keyword arguments with default value make it easy to add new behaviors to a function, especially when the function has exsisting callers.
• Optional keyword arguments should always be passed by keyword instead of by position.

Effective Python

def remidner(number, divisor):
    return number % divisor

It can be called by

reminder(20,7)
reminder(20, 7)
reminder(number=20, divisor=7)
reminder(divisor=7, number=20)

This expression is confusing.

twitter_search('@obama', False, 20, True)

twitter_search('@obama', retweets=False, numtweets=20, popular=True)

Is slightly (microseconds) slower but is worth it for the code clarity and developer time savings.