Smoothing and approximation across data plots

import numpy as np
from scipy import interpolate
import matplotlib.pyplot asplt
def spline1(x,y,point):
    f=interpolate.interp1d(x,y,kind="cubic") 
    X=np.linspace(x[0], x[-1], num=point, endpoint=True)
    Y = f(X)
    return X,Y

x = [0,6,11,20,30,40]
y = [92, 105, 114, 125, 148, 141]
a1,b1 = spline1(x,y,1000)
plt.plot(x,y,'ro', label="point")
plt.plot(a1,b1,label="interp1d")
plt.title ("spline")
plt.xlim ([-5,45])
plt.ylim ([80,160])
plt.legend(loc='lower right')
plt.grid(which='major', color='black', linestyle='-')
plt.grid(which='minor', color='black', linestyle='-')
plt.show()