python substitution %-style format string code example
Example 1: python string format
print("My name is {0} and I am {1} years old".format(name, age))
Example 2: new python string formatting
>>> f'Hello, {name}!'
'Hello, Bob!'
print("My name is {0} and I am {1} years old".format(name, age))
>>> f'Hello, {name}!'
'Hello, Bob!'