word_types = {'noun': ['bear', 'princess', 'door'],
            'verb': ['go', 'run', 'hide', 'stop', 'close', 'kill', 'eat'],
            'stop': ['in', 'of', 'at', 'to', 'from', 'the'],
            'direction': ['up', 'down', 'north', 'south',
                        'east', 'west', 'back', 'forward']}

def type_check(word):
    word = word.lower()
    for label, type in word_types.items():
            if word in type:
                return (label, word)

def type_identify(word):
    word = word.lower()
    return [ (label, word) for label, type in word_types.items() if word in type ]

def scan(sentence):
    sentence_list = sentence.split()
    for k, v in enumerate(sentence_list):
        if type_identify(v):
            sentence_list[k] = type_identify(v)[0] #needed to add [0]
        else:
            try:
                sentence_list[k] = ('number', int(v))
            except ValueError:
                sentence_list[k] = ('error', v)
    return sentence_list

return next(((label, word)
             for label, type in word_types.items()
             if word in type),
            None)