def ifo(self):
        """Return the ifo.

        If only one ifo in the ifo list this will be that ifo. Otherwise an
        error is raised.
        """
        if self.ifo_list and len(self.ifo_list) == 1:
            return self.ifo_list[0]
        else:
            errMsg = "self.ifoList must contain only one ifo to access the "
            errMsg += "ifo property. %s." %(str(self.ifo_list),)
            raise TypeError(errMsg)
Return the ifo.

        If only one ifo in the ifo list this will be that ifo. Otherwise an
        error is raised.