code: def summarize_subgraph_edge_overlap(graph: BELGraph, annotation: str = 'Subgraph') -> Mapping[str, Mapping[str, float]]:
      
      _, _, _, subgraph_overlap = calculate_subgraph_edge_overlap(graph, annotation)
      return subgraph_overlap
docs: Return a similarity matrix between all subgraphs (or other given annotation).
  
      :param annotation: The annotation to group by and compare. Defaults to :code:`"Subgraph"`
      :return: A similarity matrix in a dict of dicts
      :rtype: dict