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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 extract_words(files):
    ''' Extracts individual words form files and exports them to individual files. '''
    output_directory = 'extracted_words'
    if not os.path.exists(output_directory):
        os.makedirs(output_directory)

    for f in files:
        file_format = None
        source_segment = None
        if f.lower().endswith('.mp3'):
            file_format = 'mp3'
            source_segment = AudioSegment.from_mp3(f)
        elif f.lower().endswith('.wav'):
            file_format = 'wav'
            source_segment = AudioSegment.from_wav(f)
        if not file_format or source_segment:
            print('Unsupported audio format for ' + f)
        sentences = convert_timestamps(files)
        for s in sentences:
            for word in s['words']:
                start = float(word[1]) * 1000
                end = float(word[2]) * 1000
                word = word[0]
                total_time = end - start
                audio = AudioSegment.silent(duration=total_time)
                audio = audio.overlay(source_segment[start:end])
                number = 0
                output_path = None
                while True:
                    output_filename = word
                    if number:
                        output_filename += "_" + str(number)
                    output_filename = output_filename + '.' + file_format
                    output_path = os.path.join(output_directory, output_filename)
                    if not os.path.exists(output_path):
                        # this file doesn't exist, so we can continue
                        break
                    # file already exists, increment name and try again
                    number += 1
                print('Exporting to: ' + output_path)
                audio.export(output_path, format=file_format)