code: def get_catalog(self):
          
          catalog = Catalog()
          for fam in self.families:
              if len(fam.catalog) != 0:
                  catalog.events.extend(fam.catalog.events)
          return catalog
docs: Get an obspy catalog object from the party.
  
          :returns: :class:`obspy.core.event.Catalog`
  
          .. rubric:: Example
  
          >>> party = Party().read()
          >>> cat = party.get_catalog()
          >>> print(len(cat))
          4