Echo speaks stop/start audio

Hi Guys can anyone help,?

I’m trying to create a button in webcore that when pressed stops audio on all echo devices then when pressed again resumes, i thought pause or mute would be the obvious but can’t get either of those to work. I can stop audio with stop all devices but i can’t make that dynamic without knowing if it is currently playing music and then storing current volume and audio source to restore it on the second press. there is a store current volume & restore last volume how do they work? has anyone done this before?