docs: def create_new_model(reference,
                       duration, 
                       dt=0.025, # ms 
                       temperature=6.3, # degC
                       default_region=None,
                       parameters = None,
                       cell_for_default_population=None,
                       color_for_default_population='0.8 0 0',
                       input_for_default_population=None,
                       synapses=[],
                       simulation_seed=12345,
                       network_filename=None,
                       simulation_filename=None):
          
      ################################################################################
      ###   Build a new network
  
      net = Network(id=reference)
      net.notes = "A network model: %s"%reference
      net.temperature = temperature # degC
      if parameters:
          net.parameters = parameters
      
  
      ################################################################################
      ###   Add some regions
      
      if default_region:
          if type(default_region)==str:
              r1 = RectangularRegion(id=default_region, x=0,y=0,z=0,width=1000,height=100,depth=1000)
              net.regions.append(r1)
              default_region = r1
          else:
              net.regions.append(default_region)
  
  
      ################################################################################
      ###   Add some cells
  
      if cell_for_default_population:
          net.cells.append(cell_for_default_population)
  
  
      ################################################################################
      ###   Add some synapses
      
      for s in synapses:
          net.synapses.append(s)
  
  
  
      ################################################################################
      ###   Add some populations
  
      if cell_for_default_population:
          pop = Population(id='pop_%s'%cell_for_default_population.id, 
                              size=1, 
                              component=cell_for_default_population.id, 
                              properties={'color':color_for_default_population})
  
          if default_region:
              pop.region = default_region
              
              pop.random_layout = RandomLayout(region=default_region.id)
  
          net.populations.append(pop)
          
  
  
      ################################################################################
      ###   Add a projection
  
      '''
      net.projections.append(Projection(id='proj0',
                                        presynaptic=p0.id, 
                                        postsynaptic=p1.id,
                                        synapse='ampa'))
  
      net.projections[0].random_connectivity=RandomConnectivity(probability=0.5)'''
      
   
      ################################################################################
      ###   Add some inputs
      
      if input_for_default_population:
  
          net.input_sources.append(input_for_default_population)
  
          
          net.inputs.append(Input(id='Stim_%s'%input_for_default_population.id,
                                  input_source=input_for_default_population.id,
                                  population=pop.id,
                                  percentage=100))
          
  
  
      ################################################################################
      ###   Save to JSON format
  
      net.id = reference
  
      print(net.to_json())
      if network_filename==None:
          network_filename='%s.json'%net.id
      new_file = net.to_json_file(network_filename)
      
  
      ################################################################################
      ###   Build Simulation object & save as JSON
  
      sim = Simulation(id='Sim_%s'%reference,
                       network=new_file,
                       duration=duration,
                       dt=dt,
                       seed=simulation_seed,
                       recordTraces={'all':'*'})
  
      if simulation_filename==None:
          simulation_filename='%s.json'%sim.id
      sim.to_json_file(simulation_filename)
      
      return sim, net