运算符的运算优先级

(低) -----------------------------------------(高)

赋值运算符 => 逻辑运算符 => 关系运算符 => 算数运算符

a=,+=,/= and,or,not >= == =< */+-

闰年算法:

if(y % 400 == 0 or y % 4 == 0 and y % 100 != 0):