how to i take the last 3 characters from a sentence python code example

Example 1: how to select last 2 elements in a string python

>>>mystr = "abcdefghijkl"
>>>mystr[-4:]
'ijkl'

>>>mystr[:-4] #to select all but last 4 characters
'abcdefgh'

Example 2: last character of string in python

a = '123456789'

#to get last char, acess index -1
print(a[-1])

#this works the same as:
print(a[len(a)-1])

#instead of 1, subtract n to get string's nth char from last
#let n = 4
print(a[-4])

#result:
9
9
6