python中的十六进制到Base64，但我得到了错误的结果

如何解决python中的十六进制到Base64，但我得到了错误的结果

hex_characters = {'0': '0000','1': '0001','2': '0010','3': '0011','4': '0100','5': '0101','6': '0110','7': '0111','8': '1000','9': '1001','a': '1010','b': '1011','c': '1100','d': '1101','e': '1110','f': '1111'}
    b64_characters = {
     '000000': 'A','000001': 'B','000010': 'C','000011': 'D','000100': 'E','000101': 'F','000110': 'G','000111': 'H','001000': 'I','001001': 'J','001010': 'K','001011': 'L','001100': 'M','001101': 'N','001110': 'O','001111': 'P','010000': 'Q','010001': 'R','010010': 'S','010011': 'T','010100': 'U','010101': 'V','010110': 'W','010111': 'X','011000': 'Y','011001': 'Z','011010': 'a','011011': 'b','011100': 'c','011101': 'd','011110': 'e','011111': 'f','100000': 'g','100001': 'h','100010': 'i','100011': 'j','100100': 'k','100101': 'l','100110': 'm','100111': 'n','101000': 'o','101001': 'p','101010': 'q','101011': 'r','101100': 's','101101': 't','101110': 'u','101111': 'v','110000': 'w','110001': 'x','110010': 'y','110011': 'z','110100': '0','110101': '1','110110': '2','110111': '3','111000': '4','111001': '5','111010': '6','111011': '7','111100': '8','111101': '9','111110': '+','111111': '/'
     }
    
    def hex_to_b64(s):
        b16 = hex_characters    
        b64 = b64_characters    
        k = 0
        g = 0
        bin_list = list()      
        b64_list = list()      
        bin_string = ''         
        b64_string = ''      
        for i in s:
            b = s[k]
            bin_list.append(b16.get(b))   
            k += 1
        
        a = bin_string.join(bin_list)   
        a_split_in_six = [(a[i:i+6]) for i in range(0,len(a),6)]  
        for i in a_split_in_six:
            m = a_split_in_six[g]
            b64_list.append(b64.get(m))
            g += 1
        b64_list_without_none = ['=' if x is None else x for x in b64_list]
        lex = b64_string.join(b64_list_without_none)
        return lex
    
    
    print(hex_to_b64('4a1b48d7322394a78326cd283f0834093e65421a7e98e90e5b452d160b5d07d8'))

我写了这段代码来将一个六进制字符串转换为一个 base64 字符串，但我得到的结果是“ShtI1zIjlKeDJs0oPwg0CT5lQhp+mOkOW0UtFgtdB9=”，正确的是“ShtI1zIjlKeDJs0oPwg0CT5lQhp+mogtbgU=”（gnotfbg00）。有人能解释一下为什么我错了吗？