new_contents: #!/usr/bin/env python3
  # Copyright 2010-2021 Google LLC
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # [START program]
  # [START import]
  from ortools.graph import pywrapgraph
  # [END import]
  
  
  def main():
      """Solving an Assignment with teams of worker."""
      # [START solver]
      min_cost_flow = pywrapgraph.SimpleMinCostFlow()
      # [END solver]
  
      # [START data]
      # Define the directed graph for the flow.
      team_A = [1, 3, 5]
      team_B = [2, 4, 6]
  
      start_nodes = ([0, 0] + [11, 11, 11] + [12, 12, 12] + [
          1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6
      ] + [7, 8, 9, 10])
      end_nodes = ([11, 12] + team_A + team_B + [
          7, 8, 9, 10, 7, 8, 9, 10, 7, 8, 9, 10, 7, 8, 9, 10, 7, 8, 9, 10, 7, 8,
          9, 10
      ] + [13, 13, 13, 13])
      capacities = ([2, 2] + [1, 1, 1] + [1, 1, 1] + [
          1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
      ] + [1, 1, 1, 1])
      costs = ([0, 0] + [0, 0, 0] + [0, 0, 0] + [
          90, 76, 75, 70, 35, 85, 55, 65, 125, 95, 90, 105, 45, 110, 95, 115, 60,
          105, 80, 75, 45, 65, 110, 95
      ] + [0, 0, 0, 0])
  
      # Define an array of supplies at each node.
      supplies = [4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -4]
      source = 0
      sink = 13
      # [END data]
  
      # [START constraints]
      # Add each arc.
      for i in range(0, len(start_nodes)):
          min_cost_flow.AddArcWithCapacityAndUnitCost(start_nodes[i],
                                                      end_nodes[i],
                                                      capacities[i], costs[i])
  
      # Add node supplies.
      for i in range(0, len(supplies)):
          min_cost_flow.SetNodeSupply(i, supplies[i])
      # [END constraints]
  
      # [START solve]
      # Find the minimum cost flow between node 0 and node 10.
      status = min_cost_flow.Solve()
      # [END solve]
  
      # [START print_solution]
      if status == min_cost_flow.OPTIMAL:
          min_cost_flow.Solve()
          print('Total cost = ', min_cost_flow.OptimalCost())
          print()
          for arc in range(min_cost_flow.NumArcs()):
              # Can ignore arcs leading out of source or intermediate nodes, or into sink.
              if (min_cost_flow.Tail(arc) != 0 and min_cost_flow.Tail(arc) != 11
                      and min_cost_flow.Tail(arc) != 12
                      and min_cost_flow.Head(arc) != 13):
  
                  # Arcs in the solution will have a flow value of 1. There start and end nodes
                  # give an assignment of worker to task.
                  if min_cost_flow.Flow(arc) > 0:
                      print('Worker %d assigned to task %d.  Cost = %d' %
                            (min_cost_flow.Tail(arc), min_cost_flow.Head(arc),
                             min_cost_flow.UnitCost(arc)))
      else:
          print('There was an issue with the min cost flow input.')
          print(f'Status: {status}')
      # [END print_solution]
  
  
  if __name__ == '__main__':
      main()
  # [END program]
  
subject: Add Python balance_min_flow