declare-option -hidden str mark_saved
define-command mark-save %{
    execute-keys '"jZ'
}
define-command mark-restore %{
    execute-keys '"jz'
}

map global normal <c-s-y> ': echo hi<ret>'
# map global normal <c-Y> ': mark-save<ret>'
map global normal <c-y> ': mark-restore<ret>'