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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 _MultiStream(cls, fds):
 """Method overriden by subclasses to optimize the MultiStream behavior."""

    for fd in fds:
      fd.Seek(0)
      while True:
        chunk = fd.Read(cls.MULTI_STREAM_CHUNK_SIZE)
        if not chunk:
          break
        yield fd, chunk, None