code: def GetDefaultAgency(self):
      
      if not self._default_agency:
        if len(self._agencies) == 0:
          self.NewDefaultAgency()
        elif len(self._agencies) == 1:
          self._default_agency = self._agencies.values()[0]
      return self._default_agency
docs: Return the default Agency. If no default Agency has been set select the
      default depending on how many Agency objects are in the Schedule. If there
      are 0 make a new Agency the default, if there is 1 it becomes the default,
      if there is more than 1 then return None.