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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 parse_boolean(value):
 """ Coerce a value to boolean. :param value: the value, could be a string, boolean, or None :return: the value as coerced to a boolean """


    if value is None:
        return None

    if isinstance(value, bool):
        return value

    if isinstance(value, string_types):
        value = value.lower()
        if value == 'false':
            return False
        if value == 'true':
            return True

    raise ValueError("Could not convert value to boolean: {}".format(value))