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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 _bytes_to_str(lines):
 """ Convert all lines from byte string to unicode string, if necessary """

    if len(lines) >= 1 and hasattr(lines[0], 'decode'):
        return [line.decode('utf-8') for line in lines]
    else:
        return lines