code: def get_create_parameter(model, param):
      
      norm_name = _n(param.name)
      parameter = model.parameters.get(norm_name)
  
      if not param.unique and parameter is not None:
          return parameter
  
      if param.unique:
          pnum = 1
          while True:
              pname = norm_name + '_%d' % pnum
              if model.parameters.get(pname) is None:
                  break
              pnum += 1
      else:
          pname = norm_name
  
      parameter = Parameter(pname, param.value)
      model.add_component(parameter)
      return parameter
docs: Return parameter with given name, creating it if needed.
  
      If unique is false and the parameter exists, the value is not changed; if
      it does not exist, it will be created. If unique is true then upon conflict
      a number is added to the end of the parameter name.
  
      Parameters
      ----------
      model : pysb.Model
          The model to add the parameter to
      param : Param
          An assembly parameter object