docs: def voltage_delta_stub(grid, tree, main_branch_node, stub_node, r_preceeding,
                         x_preceedig):
      """
      Determine voltage for stub branches
  
      Parameters
      ----------
      grid : LVGridDing0
          Ding0 grid object
      tree : :networkx:`NetworkX Graph Obj< >`
          Tree of grid topology
      main_branch_node : graph node
          Node of main branch that stub branch node in connected to
      main_branch : dict
          Nodes of main branch
      r_preceeding : float
          Resitance of preceeding grid
      x_preceeding : float
          Reactance of preceeding grid
  
      Return
      ------
      :any:`float`
          Delta voltage for node
      """
      cos_phi_load = cfg_ding0.get('assumptions', 'cos_phi_load')
      cos_phi_feedin = cfg_ding0.get('assumptions', 'cos_phi_gen')
      v_nom = cfg_ding0.get('assumptions', 'lv_nominal_voltage')
      omega = 2 * math.pi * 50
  
      stub_branch = [_ for _ in grid.graph_branches_from_node(main_branch_node) if
                     _[0] == stub_node][0][1]
      r_stub = stub_branch['branch'].type['R'] * stub_branch[
          'branch'].length / 1e3
      x_stub = stub_branch['branch'].type['L'] / 1e3 * omega * \
               stub_branch['branch'].length / 1e3
      s_max_gen = [_.capacity / cos_phi_feedin
                   for _ in tree.successors(stub_node)
                   if isinstance(_, GeneratorDing0)]
      if s_max_gen:
          s_max_gen = s_max_gen[0]
          v_delta_stub_gen = voltage_delta_vde(v_nom, s_max_gen, r_stub + r_preceeding,
                                               x_stub + x_preceedig, cos_phi_feedin)
      else:
          v_delta_stub_gen = 0
  
      s_max_load = [_.peak_load / cos_phi_load
                    for _ in tree.successors(stub_node)
                    if isinstance(_, LVLoadDing0)]
      if s_max_load:
          s_max_load = s_max_load[0]
          v_delta_stub_load = voltage_delta_vde(v_nom, s_max_load, r_stub + r_preceeding,
                                                x_stub + x_preceedig, cos_phi_load)
      else:
          v_delta_stub_load = 0
  
      return [v_delta_stub_load, v_delta_stub_gen]