function checkForErrorExit ()
{
    # arg 1 must be return code, $?
    # arg 2 (remaining line) can be message to print before exiting due to non-zero exit code
    exitCode=$1
    shift
    message="$*"
    if [ -z "${exitCode}" ]
    then
        echo "PROGRAM ERROR: checkForErrorExit called with no arguments"
        exit 1
    fi
    if [ -z "${message}" ]
    then
        echo "WARNING: checkForErrorExit called without message"
        message="(Calling program provided no message)"
    fi
    if [ "${exitCode}" -ne "0" ]
    then
        echo
        echo "   ERROR. exit code: ${exitCode}  ${message}"
        echo
        exit "${exitCode}"
    fi
}