为什么我的 function 没有给我预期的 output

Question

Given a year, determine whether it is a leap year. If it is a leap year, return the Boolean True, otherwise return False.

Note that the code stub provided reads from STDIN and passes arguments to the is_leap function. It is only necessary to complete the is_leap function.

In the Gregorian calendar, three conditions are used to identify leap years:

The year can be evenly divided by 4, is a leap year, unless: The year can be evenly divided by 100, it is NOT a leap year, unless: The year is also evenly divisible by 400. Then it is a leap year.

def is_leap(year):
    leap= False

    if (year % 400 == 0) and (year % 100 == 0):
        leap = True
    elif (year % 4 ==0) and (year % 100 != 0):
        leap=True
    else:
        pass

year = int(input())
print(is_leap(year))

Input 2100 and expected output False

Answer 1

As @Grismar pointed your function is not returning anything so just add return leap to the end.

def is_leap(year):
    leap= False

    if (year % 400 == 0) and (year % 100 == 0):
        leap = True
    elif (year % 4 ==0) and (year % 100 != 0):
        leap=True
    else:
        pass
    return leap

year = int(input())
print(is_leap(year))