python - Appending to list - None result

Question

Data:

lis_t = [['q', 'w', 'e'],['r', 't', 'y']]

Expected Outcome:

lis_t = [['q', 'w', 'e', 'u'],['r', 't', 'y']]

problem description: I am trying to append to the list above however not able to append the same as it somehow results in none. Please help me understand what am I doing wrong.

Code written:

lis_t = [['q', 'w', 'e'],['r', 't', 'y']]
lis_t[0] = lis_t[0].append('u')
print(lis_t[0])
print(lis_t)

output:

None
[None, ['r', 't', 'y']]

Answer 1

do this

lis_t = [['q', 'w', 'e'],['r', 't', 'y']]
lis_t[0].append('u')
print(lis_t)