run time complexity of append in python code example

Example 1: extend in list python

subjects=["Maths","Science","Arts","Commerce"]
subjects_2=["Artificial intelligence","Statistics"]
subjects.extend(subjects_2)
print(subjects)  ## used to add more elements from other list

Example 2: append a list to another list as element

a = ['Jon', 'janni', 'Jannardhan']
b = ['28', '29', '30']
a.append(b)
print(a)
a.pop()
a.extend(b)
print(a)