trace()
{
  if [ -n "${TRACING}" ]; then
    echo "[$(date +%Y-%m-%dT%H:%M:%S%z)] ${1}" > /dev/stderr
  fi
}

trace_rc()
{
  if [ -n "${TRACING}" ]; then
    echo "[$(date +%Y-%m-%dT%H:%M:%S%z)] Last return code: ${1}" > /dev/stderr
  fi
}