shift - remove the first element of an array, and return it
Shifts the first value of the array off and returns it, shortening the array by 1 and moving everything down. If there are no elements in the array, returns the undefined value. If
ARRAY is omitted, shifts the
@ARGV array in the main program, and the
@_ array in subroutines. (This is determined lexically.) See also
unshift() do the same thing to the left end of an array that
push() do to the right end.