code: def users_activate(user):
      
      user_obj = _datastore.get_user(user)
      if user_obj is None:
          raise click.UsageError('ERROR: User not found.')
      if _datastore.activate_user(user_obj):
          click.secho('User "{0}" has been activated.'.format(user), fg='green')
      else:
          click.secho('User "{0}" was already activated.'.format(user),
                      fg='yellow')
docs: Activate a user.