<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def update(self, pop: Union[pd.DataFrame, pd.Series]):
 """Update the simulation's state to match ``pop`` Parameters pop : The data which should be copied into the simulation's state. If ``pop`` is a DataFrame only those columns included in the view's columns will be used. If ``pop`` is a Series it must have a name that matches one of the view's columns unless the view only has one column in which case the Series will be assumed to refer to that regardless of its name. """


        if not pop.empty:
            if isinstance(pop, pd.Series):
                if pop.name in self._columns:
                    affected_columns = [pop.name]
                elif len(self._columns) == 1:
                    affected_columns = self._columns
                else:
                    raise PopulationError('Cannot update with a Series unless the series name equals a column '
                                          'name or there is only a single column in the view')
            else:
                affected_columns = set(pop.columns)

            affected_columns = set(affected_columns).intersection(self._columns)
            state_table = self.manager.get_population(True)
            if not self.manager.growing:
                affected_columns = set(affected_columns).intersection(state_table.columns)

            for c in affected_columns:
                if c in state_table:
                    v = state_table[c].values
                    if isinstance(pop, pd.Series):
                        v2 = pop.values
                    else:
                        v2 = pop[c].values
                    v[pop.index] = v2

                    if v.dtype != v2.dtype:
                        # This happens when the population is being grown because extending
                        # the index forces columns that don't have a natural null type
                        # to become 'object'
                        if not self.manager.growing:
                            raise PopulationError('Component corrupting population table. '
                                                  'Old column type: {} New column type: {}'.format(v.dtype, v2.dtype))
                        v = v.astype(v2.dtype)
                else:
                    if isinstance(pop, pd.Series):
                        v = pop.values
                    else:
                        v = pop[c].values
                self.manager._population[c] = v