Does the opposite of a shift. Or the opposite of a push,
depending on how you look at it. Prepends list to the front of the
array, and returns the new number of elements in the array.
unshift(@ARGV, '-e') unless $ARGV[0] =~ /^-/;
Note the LIST is prepended whole, not one element at a time, so the
prepended elements stay in the same order. Use reverse to do the
reverse.