def clean_word(word):
    """Remove punctuation from a word and return the cleaned word."""
    pass

def is_checkable_word(word):
    """Return true if the given string is a checkable word."""
    pass

def dictionary_contains(word):
    """Return true if the given word is in the dictionary."""
    pass

def add_word(word):
    """Add a word to the dictionary, returning nothing."""
    pass

def remove_word(word):
    """Remove a word from the dictionary, returning nothing."""
    pass