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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 write_packed(self, outfile, rows):
 """ Write PNG file to `outfile`. The pixel data comes from `rows` which should be in boxed row packed format. Each row should be a sequence of packed bytes. Technically, this method does work for interlaced images but it is best avoided. For interlaced images, the rows should be presented in the order that they appear in the file. This method should not be used when the source image bit depth is not one naturally supported by PNG; the bit depth should be 1, 2, 4, 8, or 16. """


        if self.rescale:
            raise Error("write_packed method not suitable for bit depth %d" %
              self.rescale[0])
        return self.write_passes(outfile, rows, packed=True)