Printf - print format

Is there a print format in mojo، how can I rewrite this python in mojo:

def fun (arg): 
       print(f'arg = {arg}') 
bar = [5, 10, 15, 20]

def fun (arg): 
       print(f'arg = {arg}') 
bar = [5, 10, 15, 20]

Printf - print format - Modular