trapadd () {
  _trapadd_is_bash() { [[ $BASH = */bash ]]; }

  typeset _trapadd_action="$1"

  if _trapadd_is_bash; then
    _trapadd_signal=$(echo $2 | tr 'a-z' 'A-Z')
  else
    typeset -u _trapadd_signal="$2"
  fi

  typeset _trapadd_position="$3"
  typeset _trapadd_trapout="$4"
  typeset _trapadd_cur_trap=/tmp/$$.$RANDOM
  typeset _trapadd_line=""
  typeset _trapadd_abba=""

  trap -p > $_trapadd_cur_trap
  exec 9<   $_trapadd_cur_trap
  rm        $_trapadd_cur_trap

  while read -u9 -r -- _trapadd_line; do
    [[ "$_trapadd_line" = *?(SIG)$_trapadd_signal ]] || continue
    if [[ $_trapadd_position = "prepend" ]]; then
      _trapadd_line=${_trapadd_line#*\'}
      _trapadd_line="trap '$_trapadd_action; $_trapadd_line"
    else
      _trapadd_line=${_trapadd_line%%?(;)*([[:space:]])\'+([!\'])}
      _trapadd_line="$_trapadd_line; $_trapadd_action' $_trapadd_signal"
    fi
    break
  done

  exec 9>&-

  [[ -z "$_trapadd_line" ]] && {
    _trapadd_line="trap '$_trapadd_action' $_trapadd_signal"
  }

  _trapadd_abba=$(t() { trap 'printf "%s" a' EXIT; }; t; printf "%s" b)
  
  if [[ -n $_trapadd_trapout ]]
  then printf "%s\n" "$_trapadd_line"
  else if [[ $_trapadd_abba = "ab" ]]
       then trap "eval \"$_trapadd_line\"" EXIT
       else       eval  "$_trapadd_line"
       fi
  fi
}