hexer.py

def hex_to_bytearray(hex_str):
    array_len = ??? # how many bytes do you need for a hex string of length n?
    b_arr = bytearray(array_len)

    hex_to_decimal = {
        "00": 0,
        "01": 1,
        # etc. dont write this out; find a way to print out this table and then copy/paste it here
    }
    for idx, char_pair in enumerate(???): # how can you split the hex string into 2-character chunks?
        decimal_value = hex_to_decimal[char_pair]
        b_arr[idx] = decimal_value

    return b_arr