code: function(el, options) {
  
      if (typeof options === 'undefined') {
          options = {};
      }
  
      // apply defaults
      options = _.defaults(options, defaults, {
          orientation : 'left',
          labelText: '',
          // true to position the axis-label
          // when chart uses layout positioning of axis-labels is handled by layout
          position: true 
      });
  
      this._labelText = options.labelText;
      this._animDuration = options.duration;
      this._orientation = options.orientation;
      this._margin = options.margin;
      this._width = options.width;
      this._height = options.height;
      this._isPositioned = options.position;
  
      this._container = d3.select(el);
      this._g = null;
      this._text = null;
  
  }
docs: Axis label component that can be used for x or y axis
  @param {Object} el - the HTML element
  @param {string} options.labelText - the label text
  @param {string} options.orientation - supported values 'left', 'right', 'bottom'