The function transforms each character in the input string by applying a specific operation based on its type. Alphabetic characters are shifted by a fixed amount in the alphabet, while numeric characters remain unchanged. The transformed string is returned as the output.

[CODE]:
```
def transform_string(input_string):
    output_string = ""
    for char in input_string:
        if char.isalpha():
            output_string += chr((ord(char) - ord('a') + 7) % 26 + ord('a'))
        else:
            output_string += char
    return output_string
```

Please note that the code approximation may not be exactly the same as the actual function implementation, but it should provide a good approximation of the observed behavior.