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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 maps(self):
 """ A dictionary of dictionaries. Each dictionary defines a map which is used to extend the metadata. The precise way maps interact with the metadata is defined by `figure.fit._extend_meta`. That method should be redefined or extended to suit specific use cases. """

        if not hasattr(self, '_maps'):
            maps = {}
            maps['tex_symbol'] = {}
            maps['siunitx'] = {}
            maps['value_transforms'] = {
                '__default__': lambda x: round(x, 2),
            }
            self._maps = maps
        return self._maps