```
a=[1234]
#b=[]
b.append(a)
print(b)
output: [[1234], [1234]]
a=[1234]
b=[]
b.append(a)
#print(b)
#output:[[1234]]

```

I could not understand the above code when I assigned an empty list to b it's printing [[1234]] but without assigning if I append it to b it prints out [[1234],[1234]].

What's happening here?