Nothing.
string(0) ""
array(16) { [0]=> string(1) "." [1]=> string(2) ".." [2]=> string(9) "alt-php44" [3]=> string(9) "alt-php51" [4]=> string(9) "alt-php52" [5]=> string(9) "alt-php53" [6]=> string(9) "alt-php54" [7]=> string(9) "alt-php55" [8]=> string(9) "alt-php56" [9]=> string(9) "alt-php70" [10]=> string(9) "alt-php71" [11]=> string(9) "alt-php72" [12]=> string(9) "alt-php73" [13]=> string(9) "alt-php74" [14]=> string(9) "alt-php80" [15]=> string(9) "alt-php81" }