how to add a leading zero in python code example

Example 1: python convert number to string with leading zeros

str(1).zfill(2)
# 1 will be '01'

str(23).zfill(4)
# 23 will be '0023'

Example 2: python add zero to string

# add zeros in front of a string
>>> n = '4'
>>> print(n.zfill(3))
004