add the following line in your Admin > Code Injection Footer:
<script async="" src="https://cdnjs.cloudflare.com/ajax/libs/prism/1.26.0/components/prism-python.min.js"></script>
Example:
# This program adds two numbers
num1 = 1.5
num2 = 6.3
# Add two numbers
sum = num1 + num2
# Display the sum
print('The sum of {0} and {1} is {2}'.format(num1, num2, sum))