how to pass default value to {{ }} in pythonn code example

Example 1: arguments with default parameters python

def screen_size(screen_size=80):
  return screen_aize

screen_size(120)    # the screen size is 120
screen_size()		# the screen size is 80 as default

Example 2: python function parameters default value

def F(a, b=None):
    if b is None:
        b = []
    b.append(a)
    return b