'' == 0 == false
'123' == 123
'abc' == 0
'123a' == 123
'0x01' == 1
'0e123456789' == '0e987654321' == 0
[false] == [0] == [NULL] == ['']
NULL == false == 0
true == 1
md5('QNKCDZO') == '0e830400451993494058024219903391' == md5('240610708') == '0e462097431906509019562988736854'
md5([1,2,3]) == md5([4,5,6]) == NULL