index.js
function valid_leader(durations) {
    var on = durations[0];
    var off = durations[1];
    return (8900 < on && on < 9200) && (-4600 < off && off < -4350);
}
function valid_leader(durations) {
    var on = durations[0];
    var off = durations[1];
    return (8900 < on && on < 9200) && (-4600 < off && off < -4350);
}
function valid_leader ( durations ) { var on = durations [ 0 ] ; var off = durations [ 1 ] ; return ( 8900 < on && on < 9200 ) && ( - 4600 < off && off < - 4350 ) ; }
validate the leader bit
validate the leader bit