shift - remove the first element of an array, and return it
shift
ARRAY
shift
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, push, and pop. Shift and unshift do the same thing to the left end of an array that pop and push do to the right end.