[MAP] len 5 
    key[0]: [STR] len 1 value 'a'
    val[0]: [STR] len 1 value 'A'
    key[1]: [STR] len 1 value 'b'
    val[1]: [STR] len 1 value 'B'
    key[2]: [STR] len 1 value 'c'
    val[2]: [STR] len 1 value 'C'
    key[3]: [STR] len 1 value 'd'
    val[3]: [STR] len 1 value 'D'
    key[4]: [STR] len 1 value 'e'
    val[4]: [STR] len 1 value 'E'