控制结构
if 语句
# only if block
if condition:
if_true_block
# if_else block
if condition:
if_true_block
else:
if_false_block
# if_elif_else block
if condition:
if_true_block
elif condition:
elif_true_block
elif condition:
elif_true_block
else:
all_false_block
# if 嵌套 block
if outer_condition:
if inner_condition:
inner_condition_true_block
else:
inner_condition_false_block
else:
outer_if_false_block
while 结构
# while only
while condition :
while_clause
# while-else clause:
while condition:
while_clause
else:
else_cluase
for 结构
# for结构
for iter_var in iterable:
suite_to_repeat