error[preamble-requires-status]: preamble header `requires` contains items not stable enough for a `status` of `Last Call`
  --> input.md:12:10
   |
12 | requires: 20, 1337, 2048
   |          ^^^ has a less advanced status
   |                    ^^^^^ has a less advanced status
   |
   = help: valid `status` values for this proposal are: `Draft`, `Stagnant`