The function takes a string input and returns a new string with the same characters in the same order, but replaces digits with their corresponding word representation and always appends 'L' to the end.

[CODE]:
```python
def approx_function(s):
    digit_map = {
        '0': 'zero',
        '1': 'one',
        '2': 'two',
        '3': 'three',
        '4': 'four',
        '5': 'five',
