how to append in set in python at any place code example

Example: inser elemts into a set in python

list1 = [1, 1, 2, 3, 4, 4, 5]
set1 = set(list1)
set1.add(6)			# gets inserted in the set if it does not already exist
set1.add(5)			# gets ignored as it already exists in the set