docs: def jaccard(c_1, c_2):
      """
      Calculates the Jaccard similarity between two sets of nodes. Called by mroc.
  
      Inputs:  - c_1: Community (set of nodes) 1.
               - c_2: Community (set of nodes) 2.
  
      Outputs: - jaccard_similarity: The Jaccard similarity of these two communities.
      """
      nom = np.intersect1d(c_1, c_2).size
      denom = np.union1d(c_1, c_2).size
      return nom/denom