code: def diff_move(self,v,new_comm):
      
      return _c_leiden._MutableVertexPartition_diff_move(self._partition, v, new_comm)
docs: Calculate the difference in the quality function if node ``v`` is
      moved to community ``new_comm``.
  
      Parameters
      ----------
      v
        The node to move.
  
      new_comm
        The community to move to.
  
      Returns
      -------
      float
        Difference in quality function.
  
      Notes
      -----
      The difference returned by diff_move should be equivalent to first
      determining the quality of the partition, then calling move_node, and then
      determining again the quality of the partition and looking at the
      difference. In other words
  
      >>> partition = la.find_partition(ig.Graph.Famous('Zachary'),
      ...                               la.ModularityVertexPartition)
      >>> diff = partition.diff_move(v=0, new_comm=0)
      >>> q1 = partition.quality()
      >>> partition.move_node(v=0, new_comm=0)
      >>> q2 = partition.quality()
      >>> round(diff, 10) == round(q2 - q1, 10)
      True
  
      .. warning:: Only derived classes provide actual implementations, the base
                   class provides no implementation for this function.