In my country,the direct way you want to solve any problem is solve the people who submit the problem

import sys
def f1(x):
return x + 3
def f2(x):
return 2 * x
def f3(x):
return f1(f2(x))
argv1 = int(sys.argv[1])
print(f3(argv1))
 

f1(2x+3)、f2(2*x) 求f1(f2(x))