python plot subplots with customized function

Need to create multiple plots in one plot with customized function.

fig, axes = plt.subplots(nrows=2, ncols=4, sharex=True, sharey=True, figsize=(20,10)) 
for j in range(4):
        for i in range(2):
            axes[i,j].plot_multiple(df, x_column = 'date',  y_columns = ['values',  'counts'])

created a customized function to plot two different columns with different scales. but got an error

AttributeError: 'AxesSubplot' object has no attribute 'plot_multiple'

any suggestions?