习题23：更多更多的练习

# coding: utf-8
__author__ = 'www.py3study.com'
def break_words(stuff):
    '''This function will break up words for us.'''
    words = stuff.split(' ')
    return words

def sort_words(words):
    '''Sorts the words.'''
    return sorted(words)

def print_first_word(words):
    '''Prints the first word after popping it off.'''
    word = words.pop(0)
    print(word)

def print_last_word(words):
    '''Prints the last word after popping it off.'''
    word = words.pop(-1)
    print(word)

def sort_sentence(sentence):
    '''Takes in a full sentence and returns the sorted words.'''
    words = break_words(sentence)
    return sort_words(words)

def print_first_and_last(sentence):
    '''Prints the first and last words of the sentence.'''
    words = break_words(sentence)
    print_first_word(words)
    print_last_word(words)

def print_first_and_last_sorted(sentence):
    """Sorts the words then prints the first and last one."""
    words = sort_sentence(sentence)
    print_first_word(words)
    print_last_word(words)