pipe both, stdout and stderr in the fish shell

I know this has been an issue for a while and I found a lot of discussion about it, however I didn't get which would be finally a way to get it done: pipe both, stdout and stderr. In bash, this would be simply:

cmd 2>&1 | cmd2

That syntax works in fish too. A demo:

$ function cmd1
      echo "this is stdout"
      echo "this is stderr" >&2
  end

$ function cmd2
      rev
  end

$ cmd1 | cmd2
this is stderr
tuodts si siht

$ cmd1 &| cmd2
rredts si siht
tuodts si siht

Docs: https://fishshell.com/docs/current/language.html#redirects

There's also a handy shortcut, per these docs

&>

Here's the relevant quote (emphasis and white space, mine):

> As a convenience, the redirection &> can be used to direct both stdout > and stderr to the same destination. For example: > > echo hello &> all_output.txt > redirects both stdout and stderr to the file > all_output.txt. This is equivalent to echo hello > all_output.txt > 2>&1.