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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 copy_selected_sources(cls, roi, source_names):
 """Build and return a `fermipy.roi_model.ROIModel` object by copying selected sources from another such object """

        roi_new = cls.make_roi()
        for source_name in source_names:
            try:
                src_cp = roi.copy_source(source_name)
            except Exception:
                continue
            roi_new.load_source(src_cp, build_index=False)
        return roi_new