trim in pure dash

SPACES=$(printf ' \n\t')  # '\n' must not be last

trim () {

  local trim="${1#*[^$SPACES]}"

  local head=${1%?$trim}

  trim="${1%[^$SPACES]*}"

  local tail=${1#$trim?}

  # trim

  trim="${1#$head}"

  echo -n "${trim%$tail}"
}

# Test

trim '

hello

world

'

paprefs @ bookworm

cd /usr/lib

sudo ln -s pulse-16.1+dfsg1 pulse-16.1

# https://www.reddit.com/r/Ubuntu/comments/gvtzpb/ubuntu_2004_lts_x86_64_trying_to_use_paprefs_but/

# https://youtu.be/Lsgaz5s5hfs

... still does not work... :(

uau ::: hundreds of programming languages... :(

 O.o ... "ridiculous!... we need to develop one universal standard" language "that covers everyone's" syntax "use cases"... o.O?... and can unify all languages... :) ... and still have hundreds of languages... o.O?... +1 ... :D

( https://xkcd.com/927/ )