key=a val=1
key=b val=2
key=d val=4
key=e val=5
key=f val=6
key=c val=333
array(6) {
  ["a"]=>
  int(1)
  ["b"]=>
  int(2)
  ["d"]=>
  int(4)
  ["e"]=>
  int(5)
  ["f"]=>
  int(6)
  ["c"]=>
  &int(333)
}