The function appears to remove all duplicate consecutive characters from the input string. Additionally, if the last character in the string is 'n', it turns into 'G'.

[CODE]:
```python
def approx_function(s):
    result = s[0]
    for i in range(1, len(s)):
        if s[i] != s[i - 1]:
            result += s[i]
    if result[-1] == 'n':
        result = result[:-1] + 'G'
    return result
```