se {
      button_state = -1.0
    }
    console.log('click-button-sequence: ONE', button_state);
  });

  // var L = core.randi(0, 118); var U = core.randi(0, 118) + 50;
  var L = core.randi(0, 118); var U = core.randi(85, 118) + 50;
  div.append('button').attr('id', 'subbtn2').html('TWO');
  div.append('br');
  d3.select('#subbtn2').attr('style', 'position:absolute; left:'+L+'px; top:'+U+'px');
  d3.select('#subbtn2').on('click', function(){
    if (button_state == 1.0) {
        task_state = 1.0
    } el