docs: def inventory(self, source_id):
          """
          Look at the inventory for a given source
          
          Parameters
          ----------
          source_id: int
              The id of the source to inspect
          """
          if self.n_sources==0:
              print('Please run group_sources() to create the catalog first.')
          
          else:
              
              if source_id>self.n_sources or source_id<1 or not isinstance(source_id, int):
                  print('Please enter an integer between 1 and',self.n_sources)
              
              else:
              
                  print('Source:')
                  print(at.Table.from_pandas(self.catalog[self.catalog['id']==source_id]).pprint())
                  for cat_name in self.catalogs:
                      cat = getattr(self, cat_name)
                      rows = cat[cat['source_id']==source_id]
                      if not rows.empty:
                          print('\n{}:'.format(cat_name))
                          at.Table.from_pandas(rows).pprint()