local $_;
do {
    do {
        print "> ";
        chomp( $_= <STDIN> );
    } until(  /\S/  );
} until(  'FALSE' eq cmd_select( split ' ' )  );

##</code><code>##

local $_;
do {
    print "> ";
    chomp( $_= <STDIN> );
} until(  /\S/  &&  'FALSE' eq cmd_select( split ' ' )  );

##</code><code>##

local $_;
do {
    do {
        print "> ";
        defined( $_= <STDIN> )   or  die "EOF on STDIN";
        chomp( $_ );
    } until(  /\S/  );
} until(  'FALSE' eq cmd_select( split ' ' )  );

##</code><code>##

    lots of work to get next thing;
    # possibly giving up for any of several reasons
    goto TOP   if  thing isn't interesting;
    if(  thing is invalid  ) {
        instruct;
        goto TOP;
    }
    do lots of stuff with thing;
    goto TOP   if  not last thing;
    if(  no valid things found  ) {
        complain;
        return;
    }
    finish up;
    return result;

##</code><code>##

sub get_next_interesting_thing {
    do {
        return   if  ! get_next_thing;
    } until(  interesting_thing  );
    return thing;
}
sub get_next_valid_thing {
    while(  get_next_interesting_thing  ) {
        return thing   if  valid_thing;
        instruct;
    }
    return;
}

if(  ! get_next_valid_thing  ) {
    complain;
    return;
}
do {
    do lots of stuff with thing;
} while(  get_next_valid_thing  );
finish up;
return result;