code: def ifo(self):
          
          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)
docs: Return the ifo.
  
          If only one ifo in the ifo list this will be that ifo. Otherwise an
          error is raised.