<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def write_yaml_report(func):
 """Decorator used in campaign node post-processing """


    @wraps(func)
    def _wrapper(*args, **kwargs):
        now = datetime.datetime.now()
        with Timer() as timer:
            data = func(*args, **kwargs)
            if isinstance(data, (SEQUENCES, types.GeneratorType)):
                report = dict(children=list(map(str, data)))
            elif isinstance(data, MAPPINGS):
                report = data
            else:
                raise Exception('Unexpected data type: %s', type(data))
        report['elapsed'] = timer.elapsed
        report['date'] = now.isoformat()
        if "no_exec" not in kwargs and report is not None:
            with open(YAML_REPORT_FILE, 'w') as ostr:
                yaml.dump(report, ostr, default_flow_style=False)
        return report

    return _wrapper