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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 _compute_iso_color(self):
 """ compute LineVisual color from level index and corresponding level color """

        level_color = []
        colors = self._lc
        for i, index in enumerate(self._li):
            level_color.append(np.zeros((index, 4)) + colors[i])
        self._cl = np.vstack(level_color)