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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 plot_source_topos(self, common_scale=None):
 """ Plot topography of the Source decomposition. Parameters common_scale : float, optional If set to None, each topoplot's color axis is scaled individually. Otherwise specifies the percentile (1-99) of values in all plot. This value is taken as the maximum color scale. """

        if self.unmixing_ is None and self.mixing_ is None:
            raise RuntimeError("No sources available (run do_mvarica first)")

        self._prepare_plots(True, True)

        self.plotting.plot_sources(self.topo_, self.mixmaps_, self.unmixmaps_, common_scale)