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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 _validate_bool(value):
 """ Validate a setting is a bool. Returns: bool: The value as a boolean. Raises: ValueError: If the value can't be parsed as a bool string or isn't already bool. """

    if isinstance(value, six.text_type):
        if value.strip().lower() == 'true':
            value = True
        elif value.strip().lower() == 'false':
            value = False
        else:
            raise ValueError('"{}" must be a boolean ("True" or "False")'.format(value))

    if not isinstance(value, bool):
        raise ValueError('"{}" is not a boolean value.'.format(value))

    return value