Shortcut to forward standard output and error to another command

You have command in bash and want to pipe the output and error to another command. Usually I would do like this:

command 2>&1 | tee -a log.txt

This will pipe the error and output to tee, which will append it into log.txt and print it to the console as well.

There exists a shortcut in bash 4 (via this answer):

command |& tee -a log.txt