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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def find_word_prob(word_string, word_total=sum(WORD_DISTRIBUTION.values())):
    '''
    Finds the relative probability of the word appearing given context of a base corpus.
    Returns this probability value as a float instance.
    '''
    if word_string is None:
        return 0
    elif isinstance(word_string, str):
        return WORD_DISTRIBUTION[word_string] / word_total
    else:
        raise InputError("string or none type variable not passed as argument to find_word_prob")