如何用python在地图上绘制比例尺？

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
 
plt.figure(figsize=(6, 6))
 
mymap = Basemap(llcrnrlon=-10,llcrnrlat=35, urcrnrlon=5.,urcrnrlat=45.,
             resolution='i', projection='merc', lat_0 = 39.5, lon_0 = -3.25)
 
mymap.fillcontinents(color='gray', lake_color='lightskyblue')
mymap.drawcoastlines()
mymap.drawmapboundary(fill_color='skyblue')
 
mymap.drawmeridians(np.arange(-10, 5 + 0.001, 5), labels=[1, 1, 1, 1])
mymap.drawparallels(np.arange(35, 45 + 0.001, 5), labels=[1, 1, 1, 1])
 
mymap.drawmapscale(-4., 36.0, 0.25, 39.5, 500, barstyle='fancy')
mymap.drawmapscale(2., 36.0, 4.25, 39.5, 500, fontsize = 10)
 
plt.savefig('mapscale.png', dpi=360)
plt.show()