when list is used for parameter of functions . Q. about memory stack and heap in python 3

Question

def first(a):

cnt=0
if a[0]==1:
    a[0]=0
else:
    a[0]=1

for i in range(1, len(a)):
    if a[i] != a[i - 1]:
        continue
    else:
        if a[i - 1] == T