1. Warning

  File "C:/Users/Administrator/PycharmProjects/py1/main.py", line 4
    print("is_fast is :" , is_fast)
    ^
IndentationError: expected an indented block

Code:

def tll(is_fast=True):
    if not is_fast:
    print("is_fast is :" , is_fast)

is_fast=False
tll(is_fast)

Reason:(红色部分的空格对齐)

def tll(is_fast=True):
    if not is_fast:
        print("is_fast is :" , is_fast)

is_fast=False
tll(is_fast)