according to pep8 coding style guidelines how should constant value be named in python code example

Example 1: camelcase naming convention python

# CamelCase is the way you are meant to name classes:
class ExampleClass(self):
  pass
# Start each word with a capital
# Don't seperate words with underscores

Example 2: pep 8 function

# Pep 8 Style Guide for function definition. Function names are snake case
def function_name():

Example 3: python code style

This python pep sums it up: https://www.python.org/dev/peps/pep-0008/