python list of null values

As shown below: a = [ 'Name', 'school number', 'Sex', '', 'seat number', '', 'school'] assign null values:

 

Method One: if statement

a=['姓名','学号','性别','','座位号','','学校']

for i in range(len(a)):
    if a[i] =='':
        a[i]='空值'

Method Two: if else statements

aaa=[]
for i in a:
    if i=='':
        i='空值'
    else:
        i=i
    aaa.append(i)