problem on generating more data points and plotting

I am able to plot the stair-step like plot as attached using the below code

import numpy as np
from scipy.interpolate import interp1d
import matplotlib.pyplot as plt

x = np.array([3.45, 3.88, 3.99, 4.33])
y = np.array([14.0, 11.0, 14.0, 31.0])
y = np.cumsum(y)
y0 = np.array([0])
x0 = np.interp([0], y, x)
x = np.concatenate([x0, x])
y = np.concatenate([y0, y])

# Plot
fig, ax = plt.subplots()
ax.step(x, y, color='r', where='post')
ax.set_xlim(2, 5)
ax.set_ylim(0, y.max())
ax.invert_yaxis()
plt.show()

#####################################################

Now I need to generate more data points of x and y using interpolation function and want to generate same plot as above code produced(depicted above). I tried the below mentioned code but it produces different plot(depicted below), But definition says after interpolation, we should have the same plot, we just have more data points.

import numpy as np
from scipy.interpolate import interp1d
import matplotlib.pyplot as plt

x = np.array([3.45, 3.88, 3.99, 4.33])
y = np.array([14.0, 11.0, 14.0, 31.0])
y = np.cumsum(y)
y0 = np.array([0])
x0 = np.interp([0], y, x)
x = np.concatenate([x0, x])
y = np.concatenate([y0, y])

# I need to generate more data points
NUM = 100  # modify the number of points
funct = interp1d(x, y, kind='next')
x_cont = np.linspace(x[0], x[-1], NUM)
y_cont = funct(x_cont)

# Plot
fig, ax1 = plt.subplots()
ax1.step(x_cont, y_cont, color='r', where='post')
ax1.set_xlim(2, 5)
ax1.set_ylim(0, y.max())
ax1.invert_yaxis()
plt.show()

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