# Open co-process
co_process_program |&
while read -p output
do
    if ((input_required == true))
    then
        input="just do some work";
        print -p $input;
    fi

    if [[ $output = +(*done*) ]]
    then
        input="do something else";
        print -p $input;
    fi

    if [[ $output = +(*finished*) ]]
    then
        input="time to go";
        print -p $input;
        break;
    fi
done