code: def partition_pair(bif_point):
      '''Calculate the partition pairs at a bifurcation point
  
      The number of nodes in each child tree is counted. The partition
      pairs is the number of bifurcations in the two daughter subtrees
      at each branch point.'''
      n = float(sum(1 for _ in bif_point.children[0].ipreorder()))
      m = float(sum(1 for _ in bif_point.children[1].ipreorder()))
      return (n, mf partition_pair(bif_point):
      '''Calculate the partition pairs at a bifurcation point
  
      The number of nodes in each child tree is counted. The partition
      pairs is the number of bifurcations in the two daughter subtrees
      at each branch point.'''
      n = float(sum(1 for _ in bif_point.children[0].ipreorder()))
      m = float(sum(1 for _ in bif_point.children[1].ipreorder()))
      return (n, m)
docs: Calculate the partition pairs at a bifurcation point
  
      The number of nodes in each child tree is counted. The partition
      pairs is the number of bifurcations in the two daughter subtrees
      at each branch point.