How to use the ortools.sat.python.cp_model.CpSolverSolutionCallback function in ortools

#----------------------------------------------------------------------------
# Command line arguments.
PARSER = argparse.ArgumentParser()
PARSER.add_argument(
    '--problem_instance', default=0, type=int, help='Problem instance.')
PARSER.add_argument(
    '--output_proto',
    default='',
    help='Output file to write the cp_model proto to.')
PARSER.add_argument('--params', default='', help='Sat solver parameters.')


#----------------------------------------------------------------------------
# Intermediate solution printer
class SolutionPrinter(cp_model.CpSolverSolutionCallback):
  """Print intermediate solutions."""

  def __init__(self, makespan):
    cp_model.CpSolverSolutionCallback.__init__(self)
    self.__solution_count = 0
    self.__makespan = makespan

  def OnSolutionCallback(self):
    print('Solution %i, time = %f s, objective = %i, makespan = %i' %
          (self.__solution_count, self.WallTime(), self.ObjectiveValue(),
           self.Value(self.__makespan)))
    self.__solution_count += 1


def main(args):
  """Solves the scheduling with transitions problem."""

def __init__(self, variables):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self.__variables = variables
        self.__solution_count = 0

In order to make this process easier, we present a mathematical
formulation that models the seating chart problem. This model can
be solved to find the optimal arrangement of guests at tables.
At the very least, it can provide a starting point and hopefully
minimize stress and arguments.

Adapted from
https://github.com/google/or-tools/blob/master/examples/csharp/wedding_optimal_chart.cs
"""

from __future__ import print_function
import time
from ortools.sat.python import cp_model


class WeddingChartPrinter(cp_model.CpSolverSolutionCallback):
    """Print intermediate solutions."""

    def __init__(self, seats, names, num_tables, num_guests):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self.__solution_count = 0
        self.__start_time = time.time()
        self.__seats = seats
        self.__names = names
        self.__num_tables = num_tables
        self.__num_guests = num_guests

    def on_solution_callback(self):
        current_time = time.time()
        objective = self.ObjectiveValue()
        print("Solution %i, time = %f s, objective = %i" %
              (self.__solution_count, current_time - self.__start_time,

# 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.
"""Example of a simple nurse scheduling problem."""

# [START program]
# [START import]
from __future__ import print_function
from ortools.sat.python import cp_model

# [END import]


# [START solution_printer]
class NursesPartialSolutionPrinter(cp_model.CpSolverSolutionCallback):
    """Print intermediate solutions."""

    def __init__(self, shifts, num_nurses, num_days, num_shifts, sols):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self._shifts = shifts
        self._num_nurses = num_nurses
        self._num_days = num_days
        self._num_shifts = num_shifts
        self._solutions = set(sols)
        self._solution_count = 0

    def on_solution_callback(self):
        if self._solution_count in self._solutions:
            print('Solution %i' % self._solution_count)
            for d in range(self._num_days):
                print('Day %i' % d)

def __init__(self, wife, husband):
    cp_model.CpSolverSolutionCallback.__init__(self)
    self.__wife = wife
    self.__husband = husband
    self.__solution_count = 0
    self.__n = len(wife)

#
# 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.
"""Solves a simple shift scheduling problem."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from ortools.sat.python import cp_model


class SolutionPrinter(cp_model.CpSolverSolutionCallback):
    """Print intermediate solutions."""

    def __init__(self, num_vendors, num_hours, possible_schedules,
                 selected_schedules, hours_stat, min_vendors):
        cp_model.CpSolverSolutionCallback.__init__(self)
        self.__solution_count = 0
        self.__num_vendors = num_vendors
        self.__num_hours = num_hours
        self.__possible_schedules = possible_schedules
        self.__selected_schedules = selected_schedules
        self.__hours_stat = hours_stat
        self.__min_vendors = min_vendors

    def on_solution_callback(self):
        """Called at each new solution."""
        self.__solution_count += 1