This function adds a zero to each item in the list. 

```
def add_column(matrix):
"""
  >>> m = [[0, 0], [0, 0]]
  >>> add_column(m)
  [[0, 0, 0], [0, 0, 0]]
  >>> n = [[3, 2], [5, 1], [4, 7]]
  >>> add_column(n)
  [[3, 2, 0], [5, 1, 0], [4, 7, 0]]
  >>> n
  [[3, 2], [5, 1], [4, 7]]
"""
    new_list=matrix[:]
    for i in range(len(new_list)):
        new_list[i].append(0)
    return new_list

```

It's changing the parameter that I pass it rather than creating a new object of it.
How do I make it so that I get the expected results?

```
>>> n = [[3, 2], [5, 1], [4, 7]]
>>> g = add_column(n)

```

**Expected:**

```
>>> print n
[[3, 2], [5, 1], [4, 7]]

>>> print g
[[3, 2, 0], [5, 1, 0], [4, 7, 0]]

```

**Actual Result:**

```
>>> print n
[[3, 2, 0], [5, 1, 0], [4, 7, 0]]

>>> print g
[[3, 2, 0], [5, 1, 0], [4, 7, 0]]

```