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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 topng(self, path, prefix='image', overwrite=False):
 """ Write 2d images as PNG files. Files will be written into a newly-created directory. Three-dimensional data will be treated as RGB channels. Parameters path : string Path to output directory, must be one level below an existing directory. prefix : string String to prepend to filenames. overwrite : bool If true, the directory given by path will first be deleted if it exists. """

        from thunder.images.writers import topng
        # TODO add back colormap and vmin/vmax
        topng(self, path, prefix=prefix, overwrite=overwrite)