code: def set_sim_params(self, nparams, attr_params):
          
          for name, value in nparams.items():
              val = value[0] if value[0] is not None else 'none'
              self.h5file.create_array('/parameters', name, obj=val,
                                       title=value[1])
          for name, value in attr_params.items():
              self.h5file.set_node_attr('/parameters', name, value)
docs: Store parameters in `params` in `h5file.root.parameters`.
  
          `nparams` (dict)
              A dict as returned by `get_params()` in `ParticlesSimulation()`
              The format is:
              keys:
                  used as parameter name
              values: (2-elements tuple)
                  first element is the parameter value
                  second element is a string used as "title" (description)
          `attr_params` (dict)
              A dict whole items are stored as attributes in '/parameters'