hex2dec

def hex2dec(ahex:str):
    ahex = ahex[::-1].upper()
    result = 0
    for i in range(0, len(ahex)):
        buff = ahex[i]
        if not buff.isdigit():
            if not buff in ["A","B","C","D","E","F"]:
                return None
            buff = {"A":"10",
                    "B":"11",
                    "C":"12",
                    "D":"13",
                    "E":"14",
                    "F":"15"}.get(buff,0)
        result += int(buff) * 16**i

    return result

valh = "ada"
print(valh, hex2dec(valh),hex2dec(valh) == int(valh, 16))