def get_source_node(node):
 source = (node.registered_from or node.forked_from)
 if (source is None):
  return None
 if check_node(source):
  return source
 return get_source_node(source)

def get_source_node ( node ) : source = ( node . registered_from or node . forked_from ) if ( source is None ) : return None if check_node ( source ) : return source return get_source_node ( source )
recursively search for source node .