Can you explain why we take the range differently rather than simply range(len(lst))

##5.22 Implement the function pairSum () that takes as input ##a list of distinct integers lst ##and an integer n, and prints the indexes of all pairs of ##values in lst that sum up to n. ##Chapter 5 Problems 157 ##>>> pairSum ( [7, 8, 5, 3, 4, 6], 11) ##04 ##1 3 ##2 5 def pairSum (lst, x): 'prints the indexes of all pairs of values in list lst that sum up to n' for i in range (len (1st)-1): # left index in pair for j in range (i+1, (len (lst))): # right index in pair if lst[i]+lst[j] == x:/ print(i,j)