ability to add administrator via command line

 How do I add another person as an administrator to either a single
>list or to my full mailman installation? I don't see this in either
>Postorius or the command line tools.

It would be useful to have a command line interface for adding extra administrators to a mailing list.

It could either be added:
 1) to the existing 'members' subcommand as an additional option on the --add command (like --admin --add <email address hidden>)
 2) to the existing 'members' subcommand as a separate post-add step (step 1: --add <email address hidden> step 2: --admin <email address hidden> to add admin rights to that existing subscriber)
 3) a new subcommand

#2 seems like a reasonable approach. #1 is limited because you could only give admin rights when first adding a user.