/* * call-seq: * dvector.shift -> number or nil * * Returns the first element of _dvector_ and removes it (shifting all * other elements down by one). Returns <code>nil</code> if the vector * is empty. * * args = Dvector[ 1, 2, 3 ] * args.shift -> 1 * args -> Dvector[ 2, 3 ] */ VALUE dvector_shift(VALUE ary) {