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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 to_yaml(value, pretty=False):
 """ Serializes the given value to YAML. :param value: the value to serialize :param pretty: whether or not to format the output in a more human-readable way; if not specified, defaults to ``False`` :type pretty: bool :rtype: str """


    if not yaml:
        raise NotImplementedError('No supported YAML library available')

    options = {
        'Dumper': BasicYamlDumper,
        'allow_unicode': True,
    }
    options['default_flow_style'] = not pretty

    return yaml.dump(value, **options).rstrip()