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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 _fit_islands(self, islands):
 """ Execute fitting on a list of islands This function just wraps around fit_island, so that when we do multiprocesing a single process will fit multiple islands before returning results. Parameters islands : list of :class:`AegeanTools.models.IslandFittingData` The islands to be fit. Returns ------- sources : list The sources that were fit. """

        self.log.debug("Fitting group of {0} islands".format(len(islands)))
        sources = []
        for island in islands:
            res = self._fit_island(island)
            sources.extend(res)
        return sources