code: function(timemark) {
      if (typeof timemark === 'number') {
        return timemark;
      }
  
      if (timemark.indexOf(':') === -1 && timemark.indexOf('.') >= 0) {
        return Number(timemark);
      }
  
      var parts = timemark.split(':');
  
      // add seconds
      var secs = Number(parts.pop());
  
      if (parts.length) {
        // add minutes
        secs += Number(parts.pop()) * 60;
      }
  
      if (parts.length) {
        // add hours
        secs += Number(parts.pop()) * 3600;
      }
  
      return secs;
    }
docs: Convert a [[hh:]mm:]ss[.xxx] timemark into seconds
  
  @param {String} timemark timemark string
  @return Number
  @private