examples: Fix main default parameter

examples/python/bus_driver_scheduling_sat.py

@@ -1989,7 +1989,7 @@ def solve_bus_driver_scheduling():
         bus_driver_scheduling(False, num_drivers)
 
 
-def main(_):
+def main(_=None):
     solve_bus_driver_scheduling()
 
 

examples/python/gate_scheduling_sat.py

@@ -28,7 +28,7 @@ from ortools.sat.python import visualization
 from ortools.sat.python import cp_model
 
 
-def main(_):
+def main(_=None):
     """Solves the gate scheduling problem."""
     model = cp_model.CpModel()
 

examples/python/golomb8.py

@@ -93,7 +93,7 @@ def solve_golomb_ruler(order):
     print(f'- total wall time: {solver.WallTime()}ms\n')
 
 
-def main(_):
+def main(_=None):
     solve_golomb_ruler(FLAGS.order)
 
 

examples/python/golomb_sat.py

@@ -85,7 +85,7 @@ def solve_golomb_ruler(order, params):
     print(f'- wall time: {solver.WallTime()}s\n')
 
 
-def main(_):
+def main(_=None):
     solve_golomb_ruler(FLAGS.order, FLAGS.params)
 
 

examples/python/hidato_sat.py

@@ -189,7 +189,7 @@ def solve_hidato(puzzle, index):
             print('  - wall time : %f s' % solver.WallTime())
 
 
-def main(_):
+def main(_=None):
     for pb in range(1, 7):
         solve_hidato(build_puzzle(pb), pb)
 

examples/python/knapsack_2d_sat.py

@@ -369,7 +369,7 @@ def solve_knapsack(model):
         solve_with_rotations(data, max_height, max_width)
 
 
-def main(_):
+def main(_=None):
     solve_knapsack(FLAGS.model)
 
 

examples/python/linear_assignment_api.py

@@ -49,7 +49,7 @@ def RunAssignmentOn4x4Matrix():
             'Some input costs are too large and may cause an integer overflow.')
 
 
-def main(_):
+def main(_=None):
     RunAssignmentOn4x4Matrix()
 
 

examples/python/pyflow_example.py

@@ -72,7 +72,7 @@ def MinCostFlow():
         print('There was an issue with the min cost flow input.')
 
 
-def main(_):
+def main(_=None):
     MaxFlow()
     MinCostFlow()
 

examples/python/rcpsp_sat.py

@@ -300,7 +300,7 @@ def SolveRcpsp(problem, proto_file, params):
     solver.Solve(model)
 
 
-def main(_):
+def main(_=None):
     rcpsp_parser = pywraprcpsp.RcpspParser()
     rcpsp_parser.ParseFile(FLAGS.input)
     SolveRcpsp(rcpsp_parser.Problem(), FLAGS.output_proto, FLAGS.params)

examples/python/shift_scheduling_sat.py

@@ -419,7 +419,7 @@ def solve_shift_scheduling(params, output_proto):
     print('  - wall time       : %f s' % solver.WallTime())
 
 
-def main(_):
+def main(_=None):
     solve_shift_scheduling(FLAGS.params, FLAGS.output_proto)
 
 

examples/python/steel_mill_slab_sat.py

@@ -736,7 +736,7 @@ def steel_mill_slab_with_mip_column_generation(problem):
         print('No solution')
 
 
-def main(_):
+def main(_=None):
     if FLAGS.solver == 'sat':
         steel_mill_slab(FLAGS.problem, FLAGS.break_symmetries)
     elif FLAGS.solver == 'sat_table':