docs: function() {
      var maxValue = 0, stacked = this.config.type.split(':')[0] == 'stacked';
      this.st.graph.eachNode(function(n) {
        var valArray = n.getData('valueArray'),
            acum = 0;
        if(!valArray) return;
        if(stacked) {
          $.each(valArray, function(v) { 
            acum += +v;
          });
        } else {
          acum = Math.max.apply(null, valArray);
        }
        maxValue = maxValue>acum? maxValue:acum;
      });
      return maxValue;
    }