You will be given two ASCII strings, `a` and `b`. Your task is write a function to determine which one of these strings is "worth" more, and return it.
A string's worth is determined by the sum of its ASCII codepoint indexes. So, for example, the string `HELLO` has a value of 372: H is codepoint 72, E 69, L 76, and O is 79. The sum of these values is 372.
In the event of a tie, you should return the first string, i.e. `a`.
def highest_value(a, b):
    return max(a, b, key=lambda stg: sum(ord(char) for char in stg))
def highest_value(a, b):
    return max(a, b, key=lambda stg: sum(ord(char) for char in stg))