Ability to add dynamic options to slash commands

This would be super useful. I mean like an ability to add dynamic options, so you can reveal one option based on whether the input for the previous one has been added.

For example, a user types a command, and only one option is visible:

/command <param>

Now, the user decides to fill out the parameter, and the second option is being revealed.

/command 1234 <another param>

This would be useful for commands like poll.