code: def classify_catalog(catalog):
      
      components = []
      islands = []
      simples = []
      for source in catalog:
          if isinstance(source, OutputSource):
              components.append(source)
          elif isinstance(source, IslandSource):
              islands.append(source)
          elif isinstance(source, SimpleSource):
              simples.append(source)
      return components, islands, simples
docs: Look at a list of sources and split them according to their class.
  
      Parameters
      ----------
      catalog : iterable
          A list or iterable object of {SimpleSource, IslandSource, OutputSource} objects, possibly mixed.
          Any other objects will be silently ignored.
  
      Returns
      -------
      components : list
          List of sources of type OutputSource
  
      islands : list
          List of sources of type IslandSource
  
      simples : list
          List of source of type SimpleSource