var_dump($array):
array(3) {
  ["foo"]=>
  string(3) "bar"
  [42]=>
  int(24)
  ["multi"]=>
  array(2) {
    ["dimensional"]=>
    array(1) {
      ["array"]=>
      string(3) "foo"
    }
    ["bisdimesional"]=>
    int(22)
  }
}

var_dump($array["foo"]):
string(3) "bar"

var_dump($array[42]):
int(24)

var_dump($array["multi"]):
array(2) {
  ["dimensional"]=>
  array(1) {
    ["array"]=>
    string(3) "foo"
  }
  ["bisdimesional"]=>
  int(22)
}

var_dump($array["multi"]["dimensional"]):
array(1) {
  ["array"]=>
  string(3) "foo"
}
var_dump($array["multi"]["dimensional"]["array"]):
string(3) "foo"