Chart.addYAxes Method
        
 Adds primary Y axes to the chart.
 
         
        Parameters
        
            - axes
            
 
            - 
                
Type: Object
ElementType: ChartAxis
An axis or array of axes. 
            - insertIndex
            
 
            - 
                
Type: Number (Integer)
(optional) An index in the yAxes array at which to insert the axis.
Optional: True 
        
        Return Value
        
Type: Number (Integer)
The new number of primary Y axes.