The function takes an input string and performs the following operations: (1) Converts the first letter of the input string to lowercase, (2) Replaces the letter 'r' with the letter 'q' in the input string.

[CODE]:
```python
def approx_function(input_string):
    first_letter = input_string[0].lower()
    rest_of_string = input_string[1:].replace("r", "q")
    return first_letter + rest_of_string
```

Please try this Python code locally to confirm if the approximate function works similarly to the original function.