pop - remove the last element from an array and return it
pop ARRAY
pop
Pops and returns the last value of the array, shortening the array by 1. Has a similar effect to
$tmp = $ARRAY[$#ARRAY--];
If there are no elements in the array, returns the undefined value. If ARRAY is omitted, pops the @ARGV array in the main program, and the @_ array in subroutines, just like shift().