docs: def set_trafo_costs(network, args,  cost110_220=7500, cost110_380=17333,
                      cost220_380=14166):
      """ Set capital costs for extendable transformers in respect
      to PyPSA [€/MVA]
      
      Parameters
      ----------
      network : :class:`pypsa.Network
          Overall container of PyPSA
      cost110_220 : capital costs for 110/220kV transformer
                      default: 7500€/MVA, source: costs for extra trafo in
                      dena Verteilnetzstudie, p. 146; S of trafo used in osmTGmod
      cost110_380 : capital costs for 110/380kV transformer
                  default: 17333€/MVA, source: NEP 2025
      cost220_380 : capital costs for 220/380kV transformer
                  default: 14166€/MVA, source: NEP 2025
  
      """
      network.transformers["v_nom0"] = network.transformers.bus0.map(
          network.buses.v_nom)
      network.transformers["v_nom1"] = network.transformers.bus1.map(
          network.buses.v_nom)
  
      network.transformers.loc[(network.transformers.v_nom0 == 110) & (
          network.transformers.v_nom1 == 220), 'capital_cost'] = cost110_220/\
          args['branch_capacity_factor']['HV']
      network.transformers.loc[(network.transformers.v_nom0 == 110) & (
          network.transformers.v_nom1 == 380), 'capital_cost'] = cost110_380/\
          args['branch_capacity_factor']['HV']
      network.transformers.loc[(network.transformers.v_nom0 == 220) & (
          network.transformers.v_nom1 == 380), 'capital_cost'] = cost220_380/\
          args['branch_capacity_factor']['eHV']
  
      return network