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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 unique_files(event_list):
 """Find the unique files Parameters event_list : list or dcase_util.containers.MetaDataContainer A list containing event dicts Returns ------- list Unique filenames in alphabetical order """


    if isinstance(event_list, dcase_util.containers.MetaDataContainer):
        return event_list.unique_files

    else:
        files = {}
        for event in event_list:
            if 'file' in event:
                files[event['file']] = event['file']

            elif 'filename' in event:
                files[event['filename']] = event['filename']

        files = list(files.keys())
        files.sort()
        return files