I am using a list to store some values. 

Sample code:

```
for i in range(3):
  print i
  lst[i] = i+1
  print lst[i]

```

But i am getting an error like this:

```
lst[i] = i+1
NameError: name 'lst' is not defined

```

Is it required to initialize an array in python? What is wrong in my code?