code: def count_subgraph_sizes(graph: BELGraph, annotation: str = 'Subgraph') -> Counter[int]:
      
      return count_dict_values(group_nodes_by_annotation(graph, annotation))
docs: Count the number of nodes in each subgraph induced by an annotation.
  
      :param annotation: The annotation to group by and compare. Defaults to 'Subgraph'
      :return: A dictionary from {annotation value: number of nodes}