Given User GO IDs, return their GO headers and other GO info.

def _get_plt_data(self, hdrgos_usr):
        """Given User GO IDs, return their GO headers and other GO info."""
        hdrgo2usrgos = self.grprobj.get_hdrgo2usrgos(hdrgos_usr)
        usrgos_actual = set([u for us in hdrgo2usrgos.values() for u in us])
        go2obj = self.gosubdag.get_go2obj(usrgos_actual.union(hdrgo2usrgos.keys()))
        return hdrgo2usrgos, go2obj