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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 _WritePartial(self, data):
 """Writes at most one chunk of data."""


    chunk = self.offset // self.chunksize
    chunk_offset = self.offset % self.chunksize
    data = utils.SmartStr(data)

    available_to_write = min(len(data), self.chunksize - chunk_offset)

    fd = self._GetChunkForWriting(chunk)
    fd.seek(chunk_offset)

    fd.write(data[:available_to_write])
    self.offset += available_to_write

    return data[available_to_write:]