how to plot standard deviation curve in python code example

Example: normal distribution curve in python

import matplotlib.pyplot as plt
import numpy as np

mu, sigma = 0.5, 0.1
s = np.random.normal(mu, sigma, 1000)

# Create the bins and histogram
count, bins, ignored = plt.hist(s, 20, density=True) # density is used in matplotlib 3.1 v and ahead
# if using matplotlib v2.1 use normed instead of density

# Plot the distribution curve
plt.plot(bins, 1/(sigma * np.sqrt(2 * np.pi)) *
    np.exp( - (bins - mu)**2 / (2 * sigma**2) ),       linewidth=3, color='y')
plt.show()